CA2259837A1

CA2259837A1 - Improvements in and relating to remote monitoring and signalling

Info

Publication number: CA2259837A1
Application number: CA002259837A
Authority: CA
Inventors: Raymond Mew; Jeanette Mew
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-07-12
Filing date: 1999-01-21
Publication date: 2000-07-21
Also published as: HK1020221A1; DE69710466D1; EP0910843B1; EP0910843A1; ATE213354T1; WO1998002859A1; CN1227650A

Abstract

An apparatus and method for remotely monitoring the performance of an electrical appliance utilising the mains power supply cables of the electrical apparatus (4,5,6). A remote unit (3) is provided which communicates, using a signal at between 90kHz and 145kHz modulated on to the A.C. power supply cable of the electrical apparatus (4,5,6), with a local processing means (17) provided in the vicinity of the electrical apparatus (4,5,6). A memory means is provided to store information relating to the performance of the electrical apparatus (4,5,6). A robust communication protocol is provided to ensure that data is not lost. A
control means is provided in the vicinity of the local processing means (17) so that the electrical apparatus (4,5,6) can be controlled via the remote unit (3). The system is primarily designed for monitoring items of street furniture (4,5,6).

Description

IMPROVEMENTS IN AND RELATING TO
REMOTE MONITORING AND SIGNALLING
This invention relates to improvements in and relating to remote monitoring and signalling, especially (but not exclusively) to improvements relating to mains signalling to monitor electrical appliances such as street furniture.
Our prior application GB 2 291 993 discloses a method and apparatus of monitoring and controlling the function of electrical apparatus (in particular but not exclusively street furniture). This application adds to and improves the teachings of GB 2 291 993.
According to a first aspect of the invention we provide a housing unit comprising a housing containing an electrical apparatus adapted in use to provide a function, monitoring means adapted in use to monitor a physical parameter of the electrical apparatus, and local processing means adapted to receive a parameter signal from the monitoring means indicative of said physical parameter and output a processed parameter signal, said output parameter signal being adapted to be communicated to a remote unit, not part of said unit, which is remote from the housing.
Preferably the local processing means has at least one of the following features a) to j):-a) the local processing means has a memory which stores data representative of the time the apparatus is operating, but not at least some other data that the local processing means monitors;
b) the local processing means is adapted to transmit signals to the remote unit on an event driven basis, transmitting upon a predetermined change in the status of said parameter, or upon receipt of a communications request;
c) the local processing means has an address which is hardware configurable;
d) the local processing means is adapted to transmit data in short bursts repeated a plurality of times in different time domains;
e) the local processing means is adapted to monitor continually the parameter status and to react to predetermined set points;
f) the local processing means is adapted to operate from a low power supply;
g) the local processing means is adapted to maintain data integrity by way of a mufti-level (e.g. five level) pre-transmission/acceptance check before data transmission from the local processing means to the remote unit occurs;
h) local processing means communication is half duplex, the local processing means having the ability to transmit or receive data, but not simultaneously;
i) the local processing means unit is adapted to control loads from a remote command;
j) the local processing means has the ability to take analogue signals direct from a mains power supply to said apparatus;

Preferably the local processing means has at least 2, at least 3, or at least 4, or at least 5 of the features a) to j). The local processing means may have all of the features a) to j).
The local processing means may also have the feature h) that the local processing means is adapted to communicate digital or analogue data up to a resolution of 10 bit with an accuracy of better than + or - 1 % by way of conversion of a typical analogue to digital result into single ASCII
characters prior to transmission, digital interpretation taking place in the local processing means and being readable in plain English directly from the point of acquisition with no further requirement for de-coding or translation, the local processing means being adapted to be ported directly into proprietary software packaging.
The communication medium may not be a bus and may be any suitable medium: perhaps a microwave link, radio link, mains borne signalling satellite link. Indeed, systems may be provided which are capable of communicating over a number of communication medium. The user may be able to select which medium the system uses. In one embodiment, a system is provided which is capable of communicating via mains borne signalling or a bus. When this system is being installed, the bus or mains is selected as the communication medium. This is advantageous because it allows a versatile system to be produced, and is more cost-effective.
The combination of the features discussed above enables us to provide a mains signalling system that has a greater range than previous systems of similar signal strength.
The invention will be described in relation to street furniture, but has wider applications. In its simplest form of one aspect of the invention street furniture such as street lamps are operated via a connection to power supply cables that feed power to a lamp post. A lamp post provides support for a light unit, or luminaire, which includes a light source. The power from the cable turns the lamp on or off.
The electrical apparatus may be a light source, adapted in use to provide light. The housing unit may be a luminaire (light unit).
It is well known that in order to ensure that an area is correctly lit by street lamps, some kind of checking needs to be performed to determine whether or not the lamps are functioning. Typical faults include a blown fuse or a faulty light source, and in the past teams of men have been employed to drive around an area looking for street lamps which are not working (and then making repairs or reporting the fault). This need for manual inspection is undesirable in many cases. For example, if a street lamp is cycling between an on state and an off state, a workman may drive past the lamp when it is in the on state, and not notice that the light is faulty.
Also some manual checkers may not be as trustworthy as desired, and many claim time for driving around inspecting lamp posts when in fact they are not. Providing a light source with monitoring means has the advantage that it is no longer necessary to employ teams of checkers as previously was the case.
This is advantageous as it enables the light unit to perform self monitoring functions and can eliminate the need for a team of workmen to monitor street lamps. By providing the monitoring means at the light units (as opposed to in the base of a lamp post) the monitoring unit may S
be moved safely out of the way of vandals. The provision of a self contained unit is also advantageous in that cost can be reduced when compared to a separate light unit and monitoring or control unit. When installing new lamp posts a head unit, or luminaire, has to be attached to S an upright post anyway, and it costs no more in installation time to install a self-checking means signalling luminaire than a standard one. The act of wiring it up is the same.
In the light unit the local processing means receives signals from the monitoring means and sends out separate signals to the remote unit. It can therefore process the monitoring means' signals itself and does not need to transmit all of the raw, original data over substantial distances.
Thus the monitoring means' signals should be less corrupted and less noisy when they are processed. Furthermore, the local processing means may send its signals to the remote unit only at certain times, for example when the remote unit is not being addressed by any other local processing means, or at regular intervals, for example every hour or once a day.
The local processing means may poll the remote unit periodically and transmit its processed data signals only when it receives back a down loading signal (or vice versa, the remote unit may poll the housing unit).
There is therefore no need to have continuous polling of the local processing means because it can process signals and store relevant data, for example statistical data, locally.
The local processing means may be arranged so that it monitors signals from the monitoring means continuously or at predetermined times.
Similarly, the remote unit may receive signals from the local processing means continuously or at predetermined times. The local processing means (or remote unit) may only store data on signals if predetermined criteria are met. The local processing means may filter out a lot of data and not transmit information relating to all monitoring means signals to the remote unit. For example, in lamp posts most lamp failures occur in the first 30 minutes following start up of the lamp. The local processing means (or the remote unit) may record data indicative of the performance of a lamp post unit for only a predetermined time (e.g. 30 minutes) following start up of the lamp. Alternatively, or additionally, the local processing means may monitor monitoring means signals, but not record data on them (for onward transmission to the remote processor) unless they fall outside (or within) a predetermined range or value.
Alternatively, the remote processor may receive signals but not record them if they are outside (or within) a predetermined range or value.
For example, a lamp post has a normal operating state. The monitoring means could be set up to ignore signals that are at the normal level, or within an allowable deviation of "normal". If the monitoring means was looking at the voltage across a particular resistor in the lamp post it might ignore signals that are within the range of, say, 5V ~ 0.5V (a 20% band of tolerance). If signals fall outside of an allowable range the local processing means records information relating to them and in due course sends signals to the remote unit. Instead of waiting for its normal polling time the local processing means may be set up to poll the remote unit as soon as an unacceptable signal has been received, or when it determines that the out-of-range sensor signal is not an error. The local processing means preferably processes a plurality of monitoring means signals that it receives and dependant upon these monitoring means' signals the local processing means preferably passes on appropriate signals to the remoie unit. Preferably the processing means processes a plurality of different physical parameters. For example it may receive and process: a) signals indication of voltage at one point; or b) voltage at a second point; or c) current at a point; or d) temperature; or e) stress or any other parameter;

or f) f) the light level being emitted from a light source; or any combination of a) to f).
Preferably the monitoring means is adapted to monitor the light intensity output from the light source. This is advantageous because the I vs. V
characteristics of the light source may vary as the source ages. The important factor when monitoring a light source is whether or not it is outputting light. Therefore, simply measuring the light intensity simplifies the monitoring process. The skilled person will appreciate that as light sources age the light output may fall. Once the light output falls below a certain level, the light source can be thought of as failed and will need replacing.
The light intensity may be measured by a light intensity monitoring means provided in the vicinity of the light source. Alternatively, the light intensity may be monitored by a light intensity monitoring device via a fibre optic cable, which has the advantage that the device to monitor the light intensity can be provided away from the light source. The light intensity monitoring means may be a photodiode. The fibre optic cable may be a polymer light guide.
The remote unit may be interrogated by a user, preferably remotely interrogated.
The local processing means receives signals from the remote unit via the mains power supply cables. The local processing means may operate a control unit to operate the light source (when the electrical apparatus is a light source) between an on and an off state. This may be in response to signals transmitted down the mains power supply cables. The local processing means may also be adapted to transmit signals back down the mains power supply cable to the remote unit. This has the advantage that it allows the local processing means to monitor the operation of the light source and send signals back to the remote unit to indicate a fault. It has the further advantage that the remote unit can send signals to the local processing means, and perhaps control the operation of the light source.
Up until now, it has been recognised that a stand alone control/monitoring signal processing unit may be provided. In particular the control/monitoring/signal processing unit has been provided in a form suitable for incorporating into the base of a street lamp, other lamp support or other electrical apparatus. This unit is then retro fitted to a standard electrical apparatus, perhaps a street lamp. Such systems are well suited to retro-fit applications in which the standard control unit (perhaps at the base of a street lamp post) is replaced with the new control/monitoring signal processing unit.
The light source may comprise an incandescent source, fluorescent lamp, SOX, SON, MN, or other light source.
In one embodiment, the present invention has the light source and the local processing means (and monitoring items) all in the single unit that is the luminaire. In another embodiment we may incorporate the local processing means in a cut out unit, for example that disclosed in our earlier patent application GB 2 261 116.
The local processing means may transmit one or more signals representative of the parameter signal of the remote unit. This has the advantage of alerting the remote unit to the various physical parameters being monitored.

Most preferably, the housing houses the control unit. This has the same advantages as having the other components in the housing; easier to install, remove from the reach of vandals, etc.
The local processing means may be adapted to receive signals via the mains power supply that provides power to the light source, and in response to the signals operate the light source. This may make the light source easy to control and monitor.
The housing unit may also include a visual indicating means. The indicating means may be adapted to produce a visual output signal representative of a physical parameter of the light source (or other electrical apparatus). For example, the visual indicating means may comprise an LED which is illuminated when the lamp should be on. This has the advantage that it makes it easier to see if there is a fault; if the LED is on but the light source is not then there is a fault, whereas if the lamp is merely not on, it is not apparent whether there is a fault.
The visual indicating means may also be adapted to indicate when the remote unit is communicating with the local processing means (or vice versa). This is advantageous when trying to find faults in the system; it is immediately apparent if there is a breakdown in communications - the visual indicating means will not indicate communication taking place.
The monitoring means may be adapted to monitor the mains voltage at the light source before and/or after the light source is lit. The monitoring means may also be adapted to monitor the voltage at the light source before and after a fuse provided to protect the light source. The monitoring means may also be adapted to monitor the current flowing through the light source. The monitoring means may comprise a plurality of sensors, each sensor being adapted to sense a different parameter of the light source. Preferably, the sensors may include a current sensor and a voltage sensor adapted to measure the current passing through and the voltage supplied to the lamp (or other electrical apparatus). Providing 5 sensors/monitoring means to detect the above mentioned parameters is advantageous in that it possible to ascertain the correct functions of the light source (or other electrical apparatus) .
Preferably the monitoring means adapted to monitor current can measure 10 load currents in the range 8w to l.2kw. This may be user configurable.
Preferably the light unit has an operating voltage of between 80 and 260 volts A.C.
Preferably the light unit is provided with input surge protection to B.S.I
class B (6kv 1.2 x 50,us). Preferably the frequency of the A.C. supply to the light unit can be in the range 45-65Hz. Most preferably the frequency of the A.C. supply is approximately 50Hz. Providing a light unit which can operate under these conditions is advantageous because it allows the unit to be used in typical conditions encountered in the market place. The unit may be also able to be used in a number of countries/areas if such a range of inputs is allowed.
The local processing means or the remote unit may be able to monitor the time the light source is on; that is emitting light. This is advantageous as it allows a company/body operating the light unit to ascertain whether the light sources are meeting the specified number of hours before failure.
The local processing means and the remote unit may be adapted, in use, to communicate in half duplex. This may ensure robust communication of data.

It rnay be possible to monitor the current flowing in the light unit in a variety of ways. This may be user configurable. One such way may be to measure the total current of the light unit including that passing S through a ballast, a capacitor and the light source. The user configurability is advantageous as it provides a flexible device which can meet a variety of customer requirements.
The remote unit and the local processing means may be adapted, in use, to modulate the signal present on the mains power supply cables at a carrier frequency of approximately 135kHz. This frequency may be a frequency which is relatively immune from noise.
The remote unit and the local processing means may incorporate phase locked loops (PLL) ensuring that the system can "lock on" to the carrier frequency.
We have experienced problems in installations with long cable lengths in which there is a voltage drop along the mains power supply cables. This may have a disastrous effect on reliable communications, and providing the PLL's can overcome this problem.
The remote unit may be provided with a memory means. The memory means may record signals sent to the remote unit from the local processing means. This has the advantage that a history of operation of the light unit (or other electrical equipment when the invention is applied to something other than a light unit) may be built up which can be reviewed to inspect how the light unit is functioning.
The memory means may be approximately 8 kilobytes. Alternatively in an improved version the memory means may be approximately 16 kilobytes. These sizes may provide convenient memory means, large enough to store a reasonable amount of data.
Preferably the local processing means is a microcontroller.
Preferably the microcontroller is provided encased in a matrix, such as a resin block. This protects the assembly of the microcontroller and associated conversion circuitry. Hitherto it has been unthinkable in such a high volume product as a monitor or a control unit for street furniture to encase a microcontroller assembly in a protective matrix. If anything goes wrong with the associated, and cheap, electronics which accompanies a microprocessor chip it is conventional to take the board upon which the microcontroller and associated circuitry are mounted out of the apparatus and see if the board can be repaired. By encasing the assembly in a matrix there is no possibility of repair. This means that a ~2-~3 microcontroller could be made useless by the failure of a 1 penny resistor.
Up until now this has meant that microcontrollers, at least in high volume, cost conscious, products have not been encapsulated in resin. By using commercially available microcontrollers they can be disposable.
Indeed, another way of looking at this aspect of the invention is as a one-shot disposable monitor assembly that incorporates a microcontroller and associated electronic circuitry encased in a matrix, adapted to monitor and process signals from an electrical apparatus.
By having a microcontroller, instead of a microprocessor we may be able to make our monitoring apparatus far smaller than would otherwise be the case.
Another problem associated with monitoring of a large number of electrical devices, such as lamp posts, is that the end user needs to know which unit is showing a problem (so that he can send someone to repair the device). Each device (or group of devices) therefore needs to indicate its own identity. Conventionally this is done by having a slightly differently encoded microchip for each local monitoring device. The local monitoring unit associated with each lamp post codes its signals so that the remote can identify it, and knows to which lamp post the signals relate. This is all very well until the microchip in a local monitor fails.
In order to replace the microchips the engineer must contact the manufacturers of the microchips, give them the identity code of the broken microchip and ask them to encode, on a one-off basis, another microchip with the same identify code (so that the remote processor will still associate the signals with the correct lamp post) . The engineer must then wait for the replacement part to arrive and then go out and fit it.
Thus the engineer usually makes two trips to the lamp post (one to determine that it is the chip that is at fault and a second to fit the replacement chip) and typically has to wait three weeks or so for the replacement chip to arrive.
In one embodiment the local processing means is provided with an identity code unit, the arrangement being such that the identity code unit can be removed from the local processing means and can be re-used with a new local processing means. However, in a preferred embodiment the remote station is provided with switches which can be configured to give the correct address. The switches may be DIL switches.
This enables us to make all of the local processing means of our light units identical, without the need to give them an identity code. This reduces their unit cost. Furthermore, since the local processing means are identical if one fails on-site an engineer can carry a spare local processing means with them to the electrical device and can replace it there and then taking out the identity code unit from the old light unit and attaching it to the new local processing means so as to create a new light unit, but with the same code unit.
The code unit may be considered to be a coding key. In an even more preferred arrangement the identity code unit comprises a plurality of coupling members adapted to co-operate with a plurality of complementary coupling members provided on the local processing means, the arrangement being such that when the code unit is mounted on the local processing means electrical connection is made between certain complementary coupling members, dependant upon the configuration of the code unit.
Instead of requiring electrical connection to provide the code any suitable interaction may be used (e.g., optical coding). The local processing means must simply produce a code signal dependant upon the code unit.
Preferably the code unit has a plurality of wires linking parts of its coupling members. If that is all the electrical content of the code unit there is very little to go wrong with it, which means the engineer will hardly ever have to replace a broken code unit.
Preferably to code the proto-code unit the user, in use, makes, or more preferably breaks, one or more connections between pairs of coupling members of the code unit. For example, the proto-code unit may be provided with 8 wires linking 8 pairs of coupling members. The engineer may have a broken code unit which he knows (from his own records) originally had linking wires nos. 1,6, and 7 broken, and linking wires nos. 2,3,4,5, and 8 intact. He therefore takes the proto-code unit and codes it to the same code as the original code unit by breaking wires 1,6, and 7 with an appropriate tool such as a small screwdriver. Alternatively manually operable switches may be provided to make or brake the connections.

The remote unit may be adapted to receive signals from a plurality of said local processing means.
Preferably there is a housing unit which comprises connection means 10 adapted, in use, to co-operate with a complementary mounting means.
The mounting means may be associated with a post (perhaps a lamp post) or other similar structure. The connection means may allow a user to attach the housing unit to a mounting relatively easily.
15 Most preferably, electrical coupling means are provided which are adapted to be connected to an electrical supply means of the post (or other similar structure). Such an electrical coupling means may allow the user to simply attach a housing unit to a mounting, connect a power supply, and so provide a piece of electrical apparatus capable of being monitored/controlled via its mains power supply wiring.
According to a second aspect of the invention we provide a method of allowing remote monitoring of an electrical apparatus to occur, comprising providing a housing means containing an electrical apparatus, a processing means and a monitoring means and causing the monitoring means to monitor at least one physical parameter of the electrical apparatus and output a parameter signal representative of the physical parameter to the processing means and further causing the processing means to communicate the processed parameter signal to a remote unit which is remote from the housing means.

Preferably the method comprises having the local processing means -remote sensor interface doing one or more of the following:
a) the local processing means monitors signals representative of said parameter, but does not store all of the data it is fed by the sensor, but does store at the local processing means data relating to the time that the electrical apparatus has been operating, b) the local processing means transmitting temporarily stored data to said remote sensor on an event driven basis, transmitting upon a change of the monitored parameter, or upon a communications request from the remote unit;
c) the data transmission from the local processing means to the remote unit being sent in a plurality of (e.g. three) short bursts in different time domain;
d) the local processing means continually monitoring its own parameter status and reacting as its parameters reach or pass predetermined set points;
e) data integrity of the data transmitted from the local processing means to the remote unit is maintained by way of a mufti-level pre transmission/acceptance check comprising one or more of f) to i);
f) ensuring that the receive signal is continually present for a minimum time (e.g. 100 milliseconds);
g) ensuring that the first bit is a particular ASCII character which initialises all receive buffers of the local processing means;
h) ensuring that the next bits of information received by the local processing means identify its address;
i) ensuring that the next bits of information contain a predetermined ASCII character and a command digit.
j) ensuring that the data stream received by the remote sensor is at a predetermined speed (e. g. 300 baud) , any extra or non ASCII characters re-setting the receive buffer of the remote unit to zero and requiring repeat transmission;
k) and in which method the local processing means and remote unit have the ability to communicate digital or analogue data up to a resolution of 10 bit with an accuracy of better than + or - 1% by way of conversion of a typical A to D result into single ASCII characters prior to transmission, digital interpretation taking place in the local processing means and being capable of being read in plain English directly from the point of acquisition with no further requirement for de-coding or translation, so that the data is adapted to be ported directly into proprietary software packaging;
1) and in which local processing means communication with the remote unit is half duplex, each unit having the ability to transmit or receive data but not simultaneously allowing the Scout unit to control loads from a remote command;
m) and the local processing means having the ability to take analogue signals direct from the mains power supply of the electrical apparatus, and n) in which the local processing means provides an analogue R.M.S. reading of load current passing through said electrical apparatus.
Preferably the method comprises doing 2, 3, 4, 5, 6, 7 or more, or all of a) to n) .
Providing a stand alone housing which contains the electrical apparatus has the advantage that it provides a safe and secure way of housing the electrical apparatus, the monitoring means and the local processing means.
The electrical apparatus may be a light source adapted to produce light in use. The housing may be a luminaire.

Preferably the method is a way of monitoring, remotely, street furniture, perhaps street lamps.
Preferably the method comprises connecting the housing means of the electrical apparatus to mounting means (e.g. lamp posts) which have already been provided. This may provide a cheap efficient way of connecting electrical apparatus (e.g. street lamps) which have the ability to be monitored.
The method may further comprise providing a housing unit which simply needs to be connected to mains power supply cables in order to provide a working electrical apparatus (e.g. a street lamp) with the ability to be remotely monitored. Not only may such a method provide a cheap efficient way of providing an electrical apparatus (e.g. a street lamp) which can be remotely monitored, it positions the expensive monitoring, and local processing means out of the reach of vandals. (These are positioned in the housing means which may be lOm above street level).
The method may allow a number of electrical apparatus to be monitored by a single remote unit. 'This has the advantage that it is much more efficient than providing a single remote unit for each piece of electrical apparatus being monitored.
The method may comprise modifying the signal present on the mains power supply cables to allow the local processing means to communicate with the remote unit. This may provide a simple way to provide communication.
The local processing means of a first piece of electrical apparatus may monitor the signal on the mains power supply cable to ensure the focal processing means on a different (second) piece of electrical apparatus monitored by the same remote unit as the first piece of electrical apparatus is not communicating with the remote unit (or the remote unit is not communicating with the second piece of electrical apparatus) when the local processing means of the first piece of electrical apparatus communicates with the remote unit. This may ensure that signals are not lost due to two local processing means attempting to communicate with the remote unit.
The method may further comprise providing control means in the electrical apparatus, which can be controlled by signals from the remote unit. This has the advantage that the electrical apparatus can be controlled by, as well as monitored by, the remote unit.
The remote unit may issue commands to the local processing means.
These may control the local processing means and/or the control means and so operate the electrical apparatus.
Alternatively or additionally the remote unit may issue commands which effect only specific local processing means and/or control means. An advantage of this is that single pieces of electrical apparatus may be controlled.
The method may comprise issuing commands from the remote unit which activate the electrical apparatus in communication with the remote unit in sequence. For instance a row of street lamps may be turned on one after another until they are all on. An advantage of this is that input surge currents are reduced which may lead to an increased life of the electrical apparatus.

Further the remote unit may issue commands to turn off (or reduce the current to) electrical apparatus (for example street lamps) at specific times. An advantage of this is that energy consumption may be reduced.

The method may comprise sending each communication between the remote unit and the local processing means/control means (or vice versa) a number of times (preferably a plurality of times, perhaps three times).
This may allow the receiving device to reconstruct a noise damaged 10 communication from the received signals. (It is unlikely that a communication will be effected the same way by noise each time it is transmitted, and therefore different parts of the signal may be damaged.
By comparing the different communications it should be possible to determine which part of the communication was damaged and maybe also 15 to repair the damage).
The remote unit may sound an alarm when an error message is received from a local processing means. This has the advantage of alerting a user of the system that something is amiss.
According to a third aspect of the invention we provide a kit for connecting to a lamp post, the kit comprising a self-contained luminaire housing monitoring means capable of monitoring in use the operation of the lamp and communicating with a remote unit.
Noise rejection is a problem when signals are transmitted from local processors to the remote unit. Transmitting information only periodically, instead of continuously reduces the likelihood of interference between signals from different local processors. Similarly, transmitting only when the remote unit indicates that there is no other signal traffic reduces noise.
Most noise is at or around the mains frequency. We may transmit a carrier signal from a local processor to a remote unit in the kHz range, S preferably at least SOkHz.
We may provide the light unit with the facility to adjust the carrier frequency. In one embodiment the mains carrier frequency is adjustable from 90-145kHz in accordance with regulatory requirements.
According to a fourth aspect of the invention we provide a method of providing a street with street lamps comprising fitting housing units according to the first aspect of the invention to lamp posts already in situ.
According to a fifth aspect of the invention we provide an item of street furniture (for example a lamp post) comprising a post, or other support structure, and a housing unit, or luminaire, in accordance with the first aspect of the invention.
According to a sixth aspect of the invention we provide a system comprising a plurality of lamp posts (or other street furniture) having a housing unit in accordance with the first aspect of the invention and a remote unit adapted, in use, to receive signals from local processing means of said units.
Preferably the system is adapted, in use, to control the operation of the electrical apparatus of the items of street furniture.
According to a seventh aspect of the invention we provide monitoring apparatus for monitoring electrical apparatus comprising a sensor to monitor a parameter of the electrical apparatus, a local processing means and a remote unit geographically separate from the electrical apparatus in which the local processing unit is adapted to process signals from the sensor and transmit its own signals to the remote unit.
S
According to an eighth aspect of the invention we provide a method of remote monitoring of an electrical apparatus, the method comprising providing a sensor to monitor a parameter of the electrical apparatus, providing a remote unit geographically separate from the electrical apparatus, at which a user can obtain information about the electrical apparatus, and further comprising providing a local processing means at the electrical apparatus, the local processing means processing the signals from the sensor before it transmits its own signals to the remote unit.
Some of the embodiments of the invention contain the feature of a housing containing the monitoring apparatus and the function-providing electrical apparatus (e.g. the light source) while other embodiments do not. It will be realised by the man skilled in the art that the features of those embodiments containing the housing which do not relate to the housing are equally applicable to the embodiments of the invention not containing the feature of the housing.
According to a ninth aspect of the invention there is provided a system capable of monitoring and controlling a number of pieces of electrical apparatus within a region, the system comprising a base station capable of communicating with at least one remote station, via a communication medium, each remote station being associated with at least one piece of electrical apparatus and further each remote station comprising a local processing means capable of communicating with the base station, a monitoring means capable of monitoring a parameter of the electrical apparatus and producing an output signal representative of the parameter and communicating the output signal to the local processing means and a control means capable of controlling the electrical apparatus upon receipt of signals from the local processing means wherein the communication medium is a bus linking at least one remote station to the base station.
The base station may be thought of as a remote unit.
An advantage of using a bus as the communication medium is that it is more secure and less prone to loss of signal due to noise than other communication mediums (for example mains borne signalling). Further, the higher security from noise damage in turn means that higher data transmission rates are achievable.
In some circumstances using mains borne signalling is convenient. It allows a signalling system to be retro fitted to existing electrical apparatus. However, it has now been found that in some circumstances the use of a bus is advantageous in view of the higher noise immunity and speed and also in view of the other more surprising results outlined below.
Further, the use of the bus allows a large increase in the number of pieces of electrical apparatus which can be controlled by the base station and also increases the speed at which the communication medium can operate.
The invention will now be described in relation to controlling lighting (and other electrical apparatus) within a tunnel. The skilled person will appreciate that the invention has wider applications. The tunnel may be the region being monitored/controlled. Alternatively, the region may be a street. The region may be an area containing a number of pieces of electrical apparatus.
The electrical apparatus may well be a motor, a fan, a pump, (or a light source) or indeed any piece of monitorable and/ or controllable electrical apparatus.
In the field of tunnel lighting the system of the current invention can greatly reduce the amount of wiring within the tunnel. In the prior art there was associated with each light source in the tunnel a number of wires (at least a live wire, a neutral wire and an earth wire) . These wires would be routed to dedicated switch gear for that particular light source.
Therefore, to control the lights within the tunnel large panels containing the switch gear would be required. As a result a large amount of wiring was required within the tunnel and also a large amount of room for the switch gear to control that lighting. An advantage of the present invention is that it can greatly reduce the amount of wiring and also largely eliminate the switch gear required.
Indeed for each luminaire or housing unit (a luminaire generally contains a number of light sources) there may simply be required live, neutral and earth cables (to power the light sources) and a bus cable. The control means of the remote station may determine whether or not the lights are on or off. The skilled person will appreciate that such an arrangement removes the need for the dedicated switch gear of the prior art and greatly reduces the amount of not only the cabling but also of the cable trays, etc.
required to house a large number of cables. In one particular embodiment fitting a system according to the ninth aspect of the invention to a tunnel rather than a system according to the prior art reduced the bill for the wiring alone by 76%. There were further savings due to a reduced requirement for buildings in view of the lower requirement for switch gear.
Preferably data transmission from the local processing means (or the remote station in general) to the base station occurs when the base station 5 polls the local processing means. Polling is advantageous because it gives the base station control over the monitoring / controlling process.
The local processing means may be polled by the base station at regular intervals and indeed, the base station may poll the local processing means 10 in a pre-set sequence. Such an arrangement allows for efficient operation of the base station.
The bus may operate at a frequency of substantially 19.2 baud. Of course, the skilled person will realise that other bus speeds are equally 15 possible and this is meant merely by way of example.
In one embodiment polling of local processing means occurs at substantially the rate of 1 per second. However, the skilled person will appreciate that this rate can be varied and the delay between consecutive 20 polls may be substantially any of the following: O.ls, 0.5s, ls, 5s, lOs, 30s or 60s.
Interrupting means may be provided which is adapted to interrupt the pre-set sequence of polling of the remote stations. This allows the base 25 station to attend to performing tasks which may be urgent in comparison to the performance of the pre-set sequence.
The interrupting means may comprise control stations which is adapted to send commands to the base station from a location remote from the base station and remote stations. This has the advantage that an operator can process (i.e. control or monitor) electrical apparatus connected to the system, in his or her vicinity even though they may be some distance from the base station. For instance, in one embodiment, an operator may be working in a tunnel several kilometres from the base station and want to alter the lighting levels within the tunnel. It is possible, using a control station, for the operator to send commands to the base station and so control the lights in their vicinity.
Once the base station has performed the tasks requested by the interrupting means it may return to the pre-set sequence of polling from where it was interrupted. Alternatively, and perhaps more preferably, the base station may continue its pre-set sequence of polling from the piece of electrical apparatus which it had to process as a result of the command from the interrupting means. As an example there may be 100 remote stations connected to a base station and the base station may poll each of the remote station in turn. The base station may have just completed polling and communicating with remote station number 49 when it receives a command from an interrupting means to process a piece of apparatus connected to remote station number 67. The base station may then process remote station 67 as requested but instead of returning to poll remote station number 50 continue its pre-set sequence of polling from apparatus number 68. This may be more efficient.
A single remote station may monitor and control a number of pieces of electrical apparatus. In the field of tunnel lighting this has a number of surprising advantages which would not be apparent to the skilled person.
The remote station may contain selecting means adapted, in use, to inform the remote station how many pieces of electrical apparatus it is controlling/monitoring. The selecting means may be DIL switches, other switches, jumpers, or any other suitable means.
The tunnel may be a road tunnel. Within a tunnel (and indeed within a street) there are various lighting requirements which must be met by the lighting provided therein. These lighting requirements can change depending on the conditions external to the tunnel. For instance if it is a particularly sunny day the lights at a tunnel entrance may be turned up to their full level so that drivers entering the tunnel can see what is inside.
The intensity of the lighting is then tailored so that the light level is reduced to the normal level for that tunnel along the length of the tunnel.
Further, the lighting at the exit of the tunnel can be increased in intensity so that as the driver leaves the tunnel their eyes may become accustomed to the brightness outside. Of course, the skilled person will appreciate that if it is not a bright day it will not be necessary to increase the intensity of the lighting.
In general the lighting level is designated by a "lighting level". There may be any number of lighting levels. However, in one embodiment there may be six lighting levels. The amount of light required determines the lighting level needed to achieve that amount of light. Generally the higher the lighting level the brighter the resultant light.
Each housing, or luminaire, within a tunnel may contain any number of lights. To achieve a certain lighting level a predetermined number of those lights may be required. For instance to achieve level six (the highest level in the example above) all of the lights within the luminaire may be required.
If a single remote station is controlling all of the lights within a particular luminaire the base station may simply send a command to that particular luminaire stating that level six lighting is required. That particular remote station would then turn on all the lights under its control.
Sensors rnay be fitted to the system informing the remote stations or base station of various parameters of the region. In one embodiment, traffic flow monitoring sensors are connected which are adapted to measure the traffic density. The system may be adapted to control the lighting level according to the traffic density. During periods of high density, high lighting levels may be used. During periods of low density, low lighting levels may be used.
The remote station (or the base station) may be adapted to compensate for the failure of a piece of electrical apparatus by utilising a second different piece of apparatus. For instance in one embodiment the remote station may be able to compensate for light source failures within a particular luminaire. For instance the luminaire may contain six light sources, four of them be required to achieve a particular lighting level. If one of the required light sources fails the remote station may turn on one of the light sources which should have not been on for that particular lighting level.
Thus the system may improve the safety of an environment.
The skilled person will appreciate that bus protocols may be used which ensure that the base station can only communicate with a single local processing means at any one time. This will ensure that there is no contention and consequent loss of data.
The remote station may be provided with a bus termination means, which may be capable of being switched into position when it is desired to terminate the bus (i.e. when the remote station is the last device on the bus). This is advantageous because it allows a single remote station to be manufactured which can be used at any position on the bus. The bus termination means may be a resistor.
Preferably the local processing means is adapted to respond to the base station when it is polled by the base station. It is however, conceivable that an apparatus could be made wherein the local processing unit communicates with the base station upon a predetermined change in the status of a parameter of the electrical apparatus.
In the system the local processing means receives signals from the monitoring means and sends out separate signals to the base station. It can therefore process the monitoring means' signals itself and does not need to transmit all of the raw, original data over substantial distances.
Thus the raw data collected by the monitoring means is less likely to be corrupted by transmission (there is less data to transmit) and the required transmission bandwidth may be reduced.
The bus may allow the base station to communicate with the remote station in full or half duplex.
According to a tenth aspect of the invention we provide a method of remote monitoring and controlling of at least one piece of electrical apparatus, comprising providing a base station and at least one remote station associated with a piece of electrical apparatus, communicating with the remote station via a communication medium wherein each remote station is provided with a monitoring means adapted to monitor a parameter of the electrical apparatus and a control means adapted to control the apparatus wherein the communication medium is a bus.

The remote station may be provided within a housing of the electrical apparatus. Providing a stand alone housing which contains the electrical apparatus has the advantage that it provides a safe and secure way of housing the electrical apparatus, the control means, the monitoring means 5 and the local processing means (which are part of the remote station).
Preferably the method is a way of monitoring, remotely, street furniture, perhaps street lamps, perhaps tunnel lights. Further, the method may be a way of monitoring, or controlling, the environment within an area. The 10 environment may be controlled by controlling electrical apparatus such as fans, air conditioning, etc.
If the method comprises connecting the housing means of the electrical apparatus to mounting means (e.g. lamp posts) which have already been 15 provided the communication medium may be connected as the housing means is connected to the mounting means.
Preferably the method comprises causing remote stations connected the base stations to compensate for failure of a first piece of electrical 20 apparatus by utilising a second different piece of apparatus. This may make the area covered by the system safer. For example the failure of light sources could be compensated for by turning on a light sources which was not previously on to compensate for the failure of another light source (which should be on).
Preferably each luminaire containing a plurality of electrical apparatus is wired with only a live, neutral, earth and bus wires. The amount of wiring for such an arrangement is greatly reduced when compared with prior art methods.

Each of the remote station may be polled by the base station. This provides a convenient way of monitoring each of the remote stations.
Indeed, the remote station may be polled in a pre-set sequence.
In some of the above aspects of the invention there is claimed a bus as the communication medium. The skilled person will appreciate that the use of the bus is not essential and that other communication medium may be suitable (for example mains borne signalling, radio links, etc.).
Embodiments of the invention will now b a described by way of example and with reference to the accompanying drawings of which:-Figure 1 shows schematically a system for monitoring and controlling the operation of a number of street lights.;
Figure 2 indicates schematically a carrier signal at a far higher frequency than noise.
Figure 3 schematically shows a polymer block encapsulating a microcontroller and associated electronics circuiting, and having a demountable identity code key;
Figure 4 shows in more detail the identity code key of Figure 3;
Figure .5 shows a monitoring system;
Figure 6 shows a schematic of a light unit in accordance with the invention;

Figure 7 shows an isometric view of a housing means suitable for use with a street lamp;
Figure 8 shows a detailed view of a remote unit 3; and Figure 9 shows schematically a system for monitoring and controlling the operation of a number of pieces of electrical apparatus.; and Figure 10 shows a schematic view of the wiring requirements for a lighting source according to the prior art and to the invention.
Figure 1 shows a plan view of a preferred embodiment of a monitoring system for light units. The system comprises a master control unit 2 which is connected to one or more remote units 3. Each remote unit controls the operation of one or more street lamps 4,5,6. Each street lamp comprises a lamp post 7,8,9 and a housing means 10,11,12 (commonly referred to as a luminaire). The street lamps 4,5,6 are supplied with electricity by mains power supply cables 1.
The housing means 10,11,12 is shown in more detail in Figure 7. The housing means comprises a light source 13 and associated starter circuit 14, a monitoring means 15 and control means 16. A local processing means 17 is also provided. The housing means 10,11,12 contains all the necessary apparatus for running the light source contained within. The monitoring means 15 comprises a plurality of sensors.
Figure 8 shows an overall view of a typical housing means 10.
In use, the remote unit 3 sends out a power-up signal to the local processing means 17 over the mains power supply line 1. This signal is received by the local processing means 17 within the housing means. The local processing means then switches on and waits for a set period, perhaps three minutes after it switches on before sending a signal back to the remote unit 3 to record its operation or status. Thus, when a remote unit 3 is connected to a plurality of street lamps 4,5,6, the remote unit will receive a series of status signals. Only those signals indicating a fault condition are stored in a memory provided in the remote unit (not shown) i.e. the fault/error signals are logged. The time at which the fault signals were received, and which street lamp issued the fault signal are also recorded.
After the reply signals have been sent to the remote unit 3, the local processing means 17 at the street lamp awaits further instruction. At this point the street lamps 4,5,6 are not yet on.
The remote unit 3 may contain a photocell which measures when the street lamps 4,5,6 need to be turned on, or alternatively, a control signal issued by the main controller 5 can be used to decide when the street lamps 4,5,6 are to be turned on. In either case, when the lamps are required to be turned on, the remote unit 3 issues a light source 13 "on" signal to the local processing means at each street lamp 4,5,6. This is done in sequence to avoid a large spike being generated. The local processing means 17 and the control means 16 at each street lamp 4,5,6 will then switch the lamp on. A predetermined period is allowed to elapse, say 10 minutes,in order to allow the light to warm up its correct source 13 to operatingtemperature. Once this time elapsed, processing has the means at each street lamp 4,5,6 further signalsback 17 then sends over the mains power supply cables 1. The signals are obtained by processing parameter signals generated by the monitoring means 15. The monitoring means 15 are adapted to measure the actual physical status of the lamp.
For example, the monitoring means 15 may include sensors for measuring lamp current, and lamp voltage. In the preferred embodiment a photodiode (or other light level monitoring means) is provided in association with each light source within the luminaire and measures the actual light level output by that light source.
It has been found that this is simpler to measure the intensity of the light output rather than trying to determine whether the light source is operating correctly be measuring the current. The I Vs V characteristics of a light source vary as the light source ages and also between different light sources and so it is hard to accurately determine the state of the light source from a voltage of current reading: it is much simpler to measure the light level directly.
Once the light source 13 is on, and has reached equilibrium (i.e. the parameters do not fluctuate substantially) the local processing means 17 sends a signal back to the remote unit 3 in the event that one of the parameters changes. This may indicate that a fault has occurred in the street lamp 4,5,6.
The housing means may also incorporate means (perhaps the control means) for controlling the light output. This may then switch the light source 13 between full output and a dimmer output in response to a signal sent from the remote unit 3 to the local processing means 17. As an example, dimming may be such that the output current is reduced by 50%
which results in a 35% saving in power. This results in a significant saving when a large number of street lamps 4,5,6 are provided. We may for example want to turn lights to their dim setting after a watershed time at night (e.g. l.OOam).

In another embodiment the system is provided with traffic flow monitoring sensors capable of determining the density of road use.
During periods of heavy road use (for example at "rush hour") the 5 lighting level is increased, but during periods of low density the lighting level can be safely reduced.
Because each street lamp 4,5,6, is individually controlled by the remote unit 3, it is possible to selectively dim one or more of a set of street 10 lamps 4,5,6 provided at each remote unit 3, or even selectively turn some off.
The light control system unit described above is advantageous in that it is event driven. A signal is only sent back to the remote unit 3 and logged 15 if it is an error signal. One particular case of interest is when a street lamp 4,5,6 continually switches between an ON and an on OFF state.
This may occur if there is a fault in the street lamp 4,5,6. In this case, it is possible to cause the local processing means in the housing means to monitor the fault signal, and if more than a given number of fault signals 20 occur within a predetermined period of time, the local processing means 17 may send an error signal to the remote unit 3 and shut down the particular, faulty, street lamp 4,5,6 until it is repaired.
The signals sent back to the remote unit 3 provide for many possible 25 improvements over the prior art method of monitoring street lamps. For example, the local processing means 17 may send a signal to the remote unit 3 indicating when a light source 13 actually turns on and when it actually turns off. The amount of time that a light source 13 is on is then recorded, and a cumulative total can be built up which is representative of 30 the "burn time" of the light source 13. This is only possible by using the monitoring means which measures the actual amount of time a light source 13 is on, as distinct from the amount of time a light source 13 is instructed to be on. Obviously, the control means 16 in the housing means may have switched a light source 13 on, but if the light source 13 is not monitored to check that it is operating, a correct check of light source 13 "burn time" cannot be made.
By monitoring the actual "burn time" of the light source 13 before failure, street lamp 4,5,6 providers can then ask for a refund or may complain if a light source 13 does not burn for the correct number of hours before failure, for example if lamps are warranted to last for 5,000 hours yet they only last 4,000 hours.
Because individual street lamp 4,5,6 control is provided, an override can be provided for individual lamps 4,5,6. For example, to meet safety codes, street lamps 4,5,6 at major junctions and roundabouts must be fully illuminated at all times. However, it is desirable to dim street lamps 4,5,6 during periods of low road use to reduce power consumption (e.g. after midnight). Using this control method, a remote unit 3 may switch some street lamps 4,5,6 to dim (or to turn off) yet retain some at full power.
The housing means may also include a visual indicating means in the form of a set of LED's 18,19,20. The LED's 18,19,20 are illuminated in response to the output signals from the local processing means 17 provided with the housing means, or may be operated by sensors remote from the housing means. A first LED 18 shows that the light source contactors are switched ON, the second LED 19 shows that the light source is dimmed, and the third LED 20 shows that the light source is fully on. The LED's 18,19,20 can be used by maintenance staff to determine if the street lamp 4,5,6 is operating correctly.
A number of diagnostic tools may also be provided with this street lamp monitoring system. The remote unit 3 may send a test signal to the local processing means 17, and the local processing means 17 may also be adapted to send a status check signal back to the remote unit 3 in response to this test signal. In this way, the integrity of the system can be checked.
Also, the ability to measure the actual status of the street lamp 4,5,6 in real time provides several additional operational advantages. Because the remote unit 3 can record the time in which signals are received and logged, the efficiency of repair work can be checked. In one example, where three street lamps 4,5,6 in a row on a motorway are all at fault, repairs must be carried out within two hours of the fault occurring. This is known as a category one fault as it represents a severe hazard. After the repair has been carried out, the local processing means 17 at the street lamp 4,5,6 will send a signal back to the remote unit 3 indicating that the street lamp 4,5,6 is now functioning, and the time that this signal is received can be logged. Thus it is possible to check that repair work is carried out in the correct time. For example, with street lighting, the replacement of lights and general repair work is usually contracted out by the provider of the street lamps and so this system allows the street lamp provider to penalise the contractors if standards are not met.
It is also possible to provide a remote link between to the remote unit 3 or the master control unit 2. This may be via a modem so that an operator can interrogate the data logged at the remote unit 3 at any time from anywhere he or she wishes, i.e. a main control office in a central location.

To summarise, we provide a self monitoring light unit for use with a street lamp 4,5,6 or any other suitable mounting. Importantly, the housing means is self contained and incorporates its own monitoring means 15. This monitoring means 15 senses a parameter such as the current or voltage at the light and may sense when a fault occurs. There may also be provided all the control means 16 and local processing means 17 required to implement a complete remote street lamp 4,5,6 monitoring system suitable for remote interrogation over a mains power supply cable 1. This system brings with it cost savings over providing a separate housing and processing/control unit such as has been provided in the past. Also, it offers the beneficial feature of being easy to install and more secure from vandalism than prior art systems. Previously systems allowing a street lamp to be remotely monitored have been fitted at the base of lamp posts 7,8,9 once all the lamp posts have been erected and wired up. This is a separate operation and is not as attractive as simply fixing the head of a lamp post to its pole or post.
Possibly a further way of looking at the invention is to provide a housing unit, or luminaire, which can be used to provide relatively easily an item of street furniture (which can be monitored).
The user is provided with a unit which simply needs to be connected to a power supply, and mounted in an appropriate manner, to provide a working item of street furniture. It may be necessary to complete a bus connection.
For instance if the item of street furniture were a street lamp the user may be provided with a luminaire which simply needs connecting to a lamp post and an electricity supply connected.

The monitoring means 15, the control means 16 and the local processing means 17 may be provided in a single module 21 which can be seen in Figure 3. Each module 21 comprises a microcontroller 30, an associated conversion circuit 31, and an identifying circuit 32 embedded in the epoxy resin block 33. A variety of input sensors S1, S2, S3 monitor suitable physical characteristics in the electronic circuit of the lamp post, for example S1 might monitor the voltage of a certain point, S2 might monitor the current at a certain point and S3 might monitor the voltage at another point, and so on. The sensors Sl, S2 and S3 measure signals S1, S2 and S3 respectively.
The microcontroller 30 is a commercially available microcontroller which is designed for a specific purposewhich is probablyother - than monitoringa lamp post. However, by an appropriatechoice of conversion circuit 31 we can enablemicrocontroller to take the 30 the input signals S1, S2, S3 and monitor them, instead of those signals which it was originally designed to monitor.
Microcontroller 30 emits its own report signals back down the power supply line, to the remote unit 3. The microcontroller has a memory (not shown) and is programmed by the remote unit 3 to report in a desired way. For example, in this particular embodiment, the remote unit 3 programs the microcontroller so that it records in its memory the performance, at 5 second intervals, of signals S1 to S3 for the first 30 minutes of the operation of the lamp post and then stops recording them (because we believe that most lamp failures occur during the first 30 minutes following start up of a lamp). The microcontroller then polls the remote unit 3 to ask for permission to down load its memory to the remote unit 3. If the remote unit 3 sees that there is no other signal traffic then the microcontroller 30 sends out a carrier signal at, say, 135kHz (schematically shown in Figure 2) and dumps its acquired date to the remote unit 3.
5 The microcontroller 30 identifies itself by including in the transmitted data an identifying code.
The identifying code is generated by the identifying circuit 32, and relies upon the configuration of a code key 34. Alternatively, a set of DIL
10 switches may be used to determine the identifying code.
The code key 34, shown in Figure 3, is removable from the resin block 33 and has 16 pins (8 sets of pairs) which are received in complementary holes 36 provided in the resin block. The key 34 is also shown in more 15 detail in Figure 4, and has 8 slots 37 in its back to enable a thin tool to be inserted into the slots 37. Behind the slots 37 are, in its original, unencoded state, respective wires 38 linking pairs of pins 35. The key 34 is encoded by breaking, or not breaking, particular wires by pushing the tool through the slots 37. In Figure 4 starting from the top, wires 4,5, 20 and 6 have been broken, leaving wires 1,2,3,5, and 8 intact which provides the key 34 with a binary code (in this example 8 bit). Each local processing means has its own, individual, and unique, coded key. It will be appreciated with an 8 bit key code we can handle 255 units on a single conductor. This could easily be upgraded to 1000 units or more simply 25 by adding two or more bits. Instead of breaking wires on an identity key the user may manipulate switches to give it an identity.
In another embodiment 10 bit codes are used to give the identity of the local processing means allowing a greater number of local processing 30 means to be connected to a remote unit (or base station).

It will be appreciated that the keys have a hardware link only, and there is no need to programme the keys at the point of installation.
The individual local processing means 17 provided in the street lamps 4,5,6 are also programmed by the remote unit 3 to keep a record of any signals which are outside of an allowable range. Although the signals Sl to S3 are recorded as a matter of course in the memory of the microcontroller 30 for the first 30 minutes, and not thereafter (as a matter of course), the microcontroller is programmed to monitor the signals continuously (say at 5 second intervals) and to keep a record of signals which are outside of an allowable error band. The microcontroller 30 may also be set up to transmit such unusual signals to the remote unit 3 periodically, or even substantially immediately (when the polling enquiry receives instructions to proceed).
It will be appreciated that the remote unit 3 could be arranged to vary the operational conduct of the microcontroller 30, for example, the master control unit 2 could be used to tell the remote unit 3 to change the period of sampling of the signals from once every 5 seconds to once every 10 seconds, or ten times a second, or any other period. Similarly, the initial recording period could be varied.
It will be appreciated that because a microcontroller is a powerful tool it can simply be reprogrammed once by the master control unit 2 and then left alone to get on with the job of monitoring/reporting. Because so much processing is done at the local processing means 17, the volume of signal traffic to the remote unit 3, and to the master control unit 2 is kept low, and this avoids confusion between the signals.

It will be appreciated that one of the benefits of the present system is that each of the blocks 33, and each of the microprocessors 30, is identical (or substantially identical). This means that we can mass produce the blocks 33 and use some and store some conveniently. If there is then a problem with one of the blocks 33 an engineer can take a replacement from our store and visit the lamp post that is having trouble (as detected by the remote unit 3, and as interrogated by the master control unit 2).
He can then simply unplug the key 34, disconnect the broken base unit of the resin block 33 and exchange it for a new base unit resin block 33, and reconnect the same key 34 to the new resin block. This will guarantee that the new resin block will generate the same identity signal (since the identity signal is generated in response to the configuration of the key 34) and the remote unit 3 will be able to correlate incoming signals with a particular lamp post. This avoids the need to have special programming of replacement chips, and reduces the down time involved in maintaining the unit.
In areas where there are special problems, for example in areas near pylons where there may be a lot of interference, we would envisage using special add-on modules to enhance particular performances of the standard resin block 33. For example, we could have a plug-in filter unit to improve the noise filtering. This may be plugged into special ports in the resin block which when provided in all resin blocks, or may be wired in in-situ.
Similarly, where there is a large distance between the items of street furniture being monitored and the remote unit 3 we could include a booster unit as a separate add-on pack.
Figure 2 also schematically illustrates another feature. The microcontroller can be programmed by the remote unit 3 to adjust the frequency of its carrier signal 40, within a range. The range shown in Figure 2 is 90kHz to 145kHz. In each case, the frequency of the carrier signal is above that of the majority of the noise 41. Although some noise is present in the frequency range 90-145kHz methods of overcoming this are discussed hereinafter.
One of the advantages of using a microcontroller, as opposed to microprocessors, is that we can have a far more powerful tool in a relatively small space. For example, we would envisage having a resin block 33 roughly 100mm x 55mm x 40mm in size. This is small enough for it to be fitted into the standard housing of a street lamp light source.
Figure 6 shows an embodiment of a monitoring system represented in a block diagrammatic form. A computer 62 running the system has dedicated software for data analysis and control. The computer 62 is connected to a monitor 64 by means of a communication link 66. Mains communication buffers 68 and 70 are provided at each end of the link 66.
Buffer 68 is connected to the computer 62 by an RS232 or 488 serial link.
Buffer 70 is connected to a microcontroller 72 through a decoder 74.
The communication link 66 between the two buffers 68 and 70 is a half duplex link over a mains supply. Information passes along the link 66 to or from the computer 62 on a phase locked loop carrier for data integrity.
Transmission can be in a frequency band 90-145kHz as opposed to the mains which is between 40 to 60Hz. For further data integrity, an automatic error correction routine is incorporated in the software in the computer 62 to replace any bits of information which are lost. The communication stream between the buffers 68 and 70 can be in a digital form or anv other suitable form.

The monitor 64 is provided with an independent power supply 76, which can be a mains supply separate from the main supply providing the link 66.
The microcontroller 72 is fed with information concerning the operation of a piece of street furniture through a number of analogue inputs. We prefer eight analogue inputs although only four inputs 78,80,82 and 84 are shown in Figure 6. Each input 78,80,82,84 is provided with a signal conditioner 86 and an opto-isolator 88. The inputs may include signals relating to an A.C. signal (such as mains supply), a D.C. signal, other current signals, or signals representative of absolute temperature or temperature change for example atmospheric temperature or temperature change. The signal conditioners 86 scale the signal up or down to be in a range suitable for the microcontroller 72 to receive. This would be, for example, in the range 0-5V. The opto-isolators 88 provide a potential cut out in case of power surges or other signals which can harm the microcontroller 72.
The microcontroller 72 has at least three outputs. In the Figure three outputs 90,92 and 94 are shown. These may be volt free outputs for external use, pulse width modulation outputs for analogue control of external loads (for example power supply to a lamp) or standard analogue D.C. voltage outputs.
The microcontroller may be provided with a plurality of further input/output ports for monitoring and control as required. In this embodiment two eight bit ports, making sixteen digital input/output ports can be used.

A key 96 (corresponding to key 34 in Figures 3 and 4) shown in the Figure may be plugged into or remove from the microcontroller 72. The key may have an eight or nine bit identity which represents the address of the microcontroller 72.

As has been discussed in the foregoing, the invention is not to be considered to be limited to the field of monitoring street furniture. It may be applied as a metering or control system to a diverse range of electrical devices or apparatus.
Other technical features worth noting about the mains signalling system are:
Two LED's 100,101 are provided on the module 21. Both of these LED's tell a user about the communication status of the module 21.
The LED 100 is identified as RX/TX and indicates that the module 21 is "listening" to the mains power supply cable 1 for the correct carrier frequency (135kHz). In normal use this LED 100 will tend to flicker as mains noise/spikes (usually in order of microseconds) can often briefly match the 135kHz carrier frequency. At this point, although the module 21 has found the correct frequency, a number of parameters need to be satisfied before the local processing means 17 will respond.
The 135kHz carrier frequency must be present for 100ms before the LED 101 (carrier accept LED) lights to indicate carrier accepted status and allow the module 21 to receive commands. This 100ms duration may be transmitted from the remote unit 3 and stops the module 21 from reacting to short duration mains noise/spikes crossing the same frequency.

On receipt of a valid carrier frequency (135kHz for more than 100ms) the module 21 opens a command channel ready to receive data. This data must start with the correct address for the module 21 (set by the key 34), then the data must only contain valid ASCII characters (numbers 0-9 and capital letter A-Z). If either of these conditions are not met the unit may cancel its data buffer and returns to zero to start again.
If all of the parameters for communication are met the module 21 will response to the remote units 3 commands.
There may be provided a photodetector to sense whether a door at the base portion of the lamp post is open or closed. Obviously these doors should be closed when the lamp is in use and it is important to know if the door has inadvertently been left open so that it can be closed. A fibre optic line may be run from the door in a base region of the lamp post to a remote unit positioned in the luminaire at the top of the lamp post. In another embodiment the remote unit could be positioned at the base region to the lamp post, having a photodetector to monitor the door, with a fibre optic run to the luminaire to sense the light output by the light source.
Communications between the remote unit 3 and the module 21 does not take place continuously but message over sent as short bursts.
Data received (3 times) by the remote unit 3, is checked (via software) for correct ASCII characters, and the 3 messages are filtered to make 1 correct string for display and the data lag, e.g. if, due to an unexpected line noise/spike, the first data message is corrupted. Such checking will also take place in communication from the remote unit 3 to the pressing means 17.

5:000 B:00000:00:00 CHO: ~ ~ 0 CH1:000 CH2:000 L:U/C/O
then, because of the time difference, the second message may be -5:000 B:~ ~ 00:00:00 CH0:000 CH1:000 CH2:000 L:U/C/O
and the third message may be -S:000 B:00000:00:00 CH0:000 CH1:000 CH2:0 ~ ~ L:U/C/O
~ ~= wrong characters The remote unit 3 removes the wrong ASCII characters and filters the 3 messages together to read the correct message -5:000 B:00000:00:00 CH0:000 CH1:000 CH2:000 L:U/C/O
This feature is important in extremely noisy environments and has proved extremely successful, often where no other devices (time clock etc.) will work.
The remote unit 3 is provided with an internal real time clock so that the time that error messages are received from various modules 21 can be logged. The remote unit in its standard form can log 650 messages, and in an improved version can log 1300 entries.
A set of commands exists some of which are global commands which will operate all of the modules 21 in communication with the remote unit 3, and some of which are individual commands which are issued specific to module 21 in communication with the remote unit 3.
Figure 8 shows a detailed view of a remote unit 3. There is provided a reset switch 150, fuse holders 151,152,153, a series of status LED's 154,155,156,157,158,159,160 (154 indicates external power supply status; 155 indicates whether the remote unit 3 is transmitting data;
156 indicates whether external control hardware is operative; 157 indicates whether the remote unit 3 has accepted an incoming carrier signal; 158 indicates whether the communication port is receiving commands; 159 indicates whether the communication port is transmitting commands; 160 indicates whether the communication port is in use), a mains switch 161, a bi-directional RS232 communication port (for connection to a laptop computer, serial printer, modem, etc.), an output block 163 for connection to various devices, a keypad 164 (for entering commands) and an LCD display 165 to display various massages, etc.
One function provided on the remote unit 3 may be a test to check communication with the modules 21.
An alternative to providing the key 34 to provide the identity for the local processing means 17 to provide a series of jumpers on the circuit board.
The presence or absence of the jumpers will indicate the code to the local processing means 17. Switches could also be used to provide the code;
the position of the switches could them indicate a 0 or a 1 much in the same way as the breaking of a wire or the presence/absence of a jumper.
In one particular embodiment controlling and monitoring the environment within a tunnel detectors are provided which monitor the height of vehicles passing through the tunnel (this may be a light beam which is broken by high vehicles). If a high vehicle is detected, barriers (or stop lights etc.) can be activated to prevent the vehicle damaging the tunnel and itself. Alternatively, other traffic could be stopped, allowing a high vehicle to pass along the centre of the tunnel (which is generally higher).
A luminaire may be manufactured which is adapted to be fitted with a remote station, but not actually fitted. The remote station can then be fitted with a remote station at a later time. Top facilitate this a plug (perhaps a shorting plug) can be fitted so that the luminaire behaves as if it were a standard luminaire. Then at a later date the plug may be removed and a remote station fitted in its place, may be with the control means connected to where the shorting plug was connected. This is advantageous in that it allows a luminaire to be provided which is no more expensive than a standard luminaire, but gives a customer the opportunity to upgrade at a later date. Of course, the remote station may also be fitted to the luminaire initially.
In summary, in one embodiment of the invention we use a Local Processing Means (usually several of these each associated with its own electrical apparatus) that performs a function, and a remote unit that controls the local processing means and receives signals from them.
The local processing means and the remote unit preferably have the following features:-local processing means (a) The local processing means is only a messenger - no data is stored at point of acquisition except burn hours (for a light).
(b) Event driven basis only - transmits on parameter status change or communications request.
(c) Address is hardware configurable 8 bit.
(d) Data transmission sent in short burst three times in slightly different time domain.
(e) Continually monitors own parameter status and only reacts to predetermined set points.

(f) Only small power supply required because of intermittent operation philosophy.
5 (g) Data integrity is maintained by way of five level pre-transmission/acceptance check.
i The receive signal must be continually present for minimum 100 milliseconds. This reduces the effect of coincidental high frequency noise falsely triggering the unit. The signal at the correct frequency for greater than 100 milliseconds could only therefore have originated from the remote unit.
ii The first bit is a particular ASCII character which initialises all receive buffers of the local processing means on the circuit.
iii The next three bits of information must be relative to the receiving local processing means and must contain its address .
iv The next two bits of information must contain the #
character (or another predetermined character) and command digit.
v The valid data stream must be received at a speed of 300 baud and any extra or non ASCII characters will re-set the receive buffer to zero and require repeat transmission.
(h) The ability to communicate digital or analogue data up to a resolution of 10 bit with an accuracy of better than + or - 1 % by 10 way of conversion of a typical A to D result into single ASCII
characters prior to transmission, unlike the standard 8 bit binary conversion. Digital interpretation takes place in the Local Processing means and can be read in plain English directly from the point of acquisition with no further requirement for de-coding or translation. It can therefore be ported directly into proprietary software packaging, e.g. MS Windows Terminal Communications Package.
(i) All local processing means communication is half duplex which means each local processing means has the ability to transmit or receive data but not simultaneously allowing the local processing means to control loads from a remote command.
(j) The ability to take analogue signals direct from the mains.
(k) True analogue R.M.S. Reading of load current.
Remote Unit (a) All save features as in the local processing means.
(b) Ability to obtain data in the field.
(c) Ability to enter data in the field.
(d) Contains in-built software tools.
(e) LCD unit.
(f) Date and time stamps all events into log.
The system of Figure 9 comprises a base station 202 connected via an RS458 bus 204 to a plurality of electrical apparatus 206, 208, 210, 212 and control stations 214. In the embodiment shown, each of the electrical apparatus comprises a luminaire containing a number of light sources.
Each remote station has its address set by a 10 bit address set by DIL
switches.
Each of the luminaires shown is identical, but the skilled person will appreciate that the luminaires connected to the base station 202 could each be different. Indeed pieces of electrical apparatus other than luminaires and light sources may be connected to the base station 202.
Each luminaire shown contains six separate light sources, two fluorescent tubes 216, 218 and four halogen bulbs 202, 222, 224, 226 (although for the sake of clarity reference numerals have been applied to only a single luminaire). Also fitted within each luminaire is a remote station 228 which contains a local processing means, a monitoring means and a control means. The local processing means can communicate with the base station 202 via the bus 204 and receive and send signals to the monitoring and control means respectively.
Each luminaire receives a single phase of a three phase power supply 230, 232, 234, together with a neutral cable. There are therefore four wires going to each luminaire, a live 230, 232, 234, a neutral, an earth and a bus 204.
The base station 202 is a fully functioning computer built into a dedicated housing. On the front panel there is a display 236, a keyboard 238, status lights (mains 240, power supply (UPS) 242, + 12VDC 244, + SVDC 246), a shielded reset button 248, a COM 1 port 250 (for external communication), a printer port 252, a joystick 254 and two input buttons 256, 258. The control station 214 has various features on its front panel: power supply status light 260, LED showing remote reset to automatic 262, an LED showing automatic running 264, an LED showing manual override occurring 266, a button for requesting automatic 268, a button for requesting manual 270, an eight segment display 272 and two input buttons 274, 276.
In use, a program is run on the base station 202 which continually polls each of the items of electrical apparatus 206, 208, 210, 212 connected to the bus 204. This polling occurs substantially every second and occurs is pre-set order (for instance luminaire 206, 208, 210, 212, etc.). As commands are input to the base station 202 signals are sent down the bus 204 instructing various functions of the electrical apparatus. For instance light sources could be turned on or off, or a fan motor turned on, etc. Information from the monitoring means can be requested.
Each remote station 228 communicating on the bus has an address which can be set by DIL switches. To communicate with a particular electrical apparatus the base station 202 sends out the required address followed by an appropriate instruction. The local processing means which has received the instruction (as part of the remote station 228) will then cause the control means to alter the electrical apparatus as desired. During the polling sequence the status of the electrical apparatus, as read by the monitoring means, is sent back to the base by each remote station 228.
The status is read by the local processing means from the monitoring means of each electrical apparatus.
Some data may be stored locally in each piece of electrical apparatus by the local processing means. This locally stored data can be read by the base station 202 as and when required by the issue of an appropriate signal sent across the bus 204. In the case of lighting the local processing means stores how long each light source to which it is connected has been operating.
As noted above each luminaire to which the base station 202 is in communication has the same arrangement of light sources 216, 218, 220, 222, 224, 226 within. However, these light sources themselves do not need be of the same wattage. In the case of lighting within a tunnel higher wattage light sources may be used near to the tunnel entrances and exits compared with those at the centre region of the tunnel.
Within a tunnel (and indeed within a streets) there are various lighting requirements which must be met by the lighting provided therein. These lighting requirements can change depending on the conditions external to the tunnel. For instance if it is a particularly sunny day the lights at a tunnel entrance may be turned up to their full level so that drivers entering the tunnel can see what is inside. The intensity of the lighting is then tailored so that the light level is reduced to the normal level inside.
Further, the lighting at the exit of the tunnel can be increased in intensity so that as the driver leaves the tunnel their eyes may become accustomed to the brightness outside. Of course, the skilled person will appreciate that if it is not a bright day it will not be necessary to increase the intensity of the lighting.
In general the lighting level is designated by a numeral representing the "lighting level". There may be any number of lighting levels. However, in this embodiment there are six lighting levels. The amount of light required determines the lighting level needed to achieve that amount of light. Generally the higher the lighting level the brighter the resultant light. The highest lighting levels may only be required at the tunnel entrances and exits and so require the highest wattage bulbs there.
5 To achieve a certain lighting level a predetermined number of those lights sources will be required. For instance to achieve level six (the highest level in the example above) all of the lights within the luminaire may be required.
10 The base station 202 will control the number of light sources which are required. This may be in response to inputs from sensors connected to the base station which may give the ambient lighting levels outside the tunnel. In the case of other electrical apparatus fan motors may be controlled in response to sensors reading the amount of pollution building 15 up within the tunnel. Or indeed, pumps may be controlled according to the level of water within a sump. The base station may give a complete environmental control of the tunnel.
If light sources within a luminaire should fail the local processor (or 20 possibly the base station 202) may be able to compensate for failure of that light source by turning on another source. The failure of the first light source will be noted and flagged for repair. Indeed, extra light sources may be turned on in different luminaires to compensate for the failure.
The control station 214 acts as an interrupting means and is positioned within the tunnel so that personnel within the tunnel can access the panel.
Manual override can be requested by the button 266. Once this is pressed the base station (if various parameters are met) will pass the control of the light sources within the vicinity of the control station 214 to the control station 214. An operator can use the buttons 274, 276 to step through the various lighting levels and the current level is displayed on the display 272.
This may be useful in a number of circumstances. For instance if work is being performed in the tunnel or if a road traffic accident has occurred more light may be required. An operator can request manual control by use of the button 266 and then step the lighting up to the required level.
These inputs to the buttons 274, 276 are sent via the bus 204 to the base station 202 which in turn will pause its polling duties and send the relevant signals to the required light sources.
Once the manual commands have been performed the base station starts it polling sequence again. However, to make the process more streamlined the base station 202 starts to poll the remote stations 228 from where it finished servicing the manual commands. For example if the base station 202 had been polling the remote station 228 of the luminaire 206 when a manual request was received which affected luminaire 210, the base station 202 would process the manual request and then return to its polling routine. However, rather than returning to poll the remote station 228 of luminaire 208 (the luminaire after luminaire 206) it would poll the remote station 228 of luminaire 212.
The differences between the wiring systems of Figures 9 and 10 will be apparent. Figure 10 shows the same luminaires, containing the same light sources (like reference numerals have been used for clarity) . However, the wiring used to power these lights sources is conventional. Each light source 216, 218, 220, 222, 224, 226 has a live and a neutral cable run to it from a remote switch gear provided in switch gear room 278. These wires are too numerous to show individually and have been represented by the bundles 280, 282, 284, 286. Clearly the prior art system has a large amount more cabling. This increases the infrastructure (cable trays, brackets, switch gear, etc.) required to operate the lighting. The skilled person will appreciate that the remote switch gear of the prior art has been replaced by the control means associated with each remote station 228.
Each luminaire can contain any number of light sources associated with a single remote station 228. However, at present it has been found that luminaires containing either one, two, or six light sources are advantageous. The remote station is provided with a number of DIL
switches (or selecting means) identifying to how many pieces of electrical apparatus it is connected. An example of a luminare 288 (or housing means) is shown in more detail in Figures 6 and 7.
The skilled person will appreciate that with each remote station 228 being able to control a number of light sources 216, 218, 220, 222, 224, 226, 290 a single base station 202 can control many thousands of light sources.
Using our presently preferred number of six light sources per remote station 228 this gives 6144 light sources per bus 204. It is possible that a single remote station 202 can control a number of buses and therefore there is a possibility that a single remote station can control tens of thousands of light sources. (Although the skilled person will appreciate that this is more than can be addressed using a 10 bit address).
The bus 4 used in one embodiment (the RS485) allows 255 remote units 228 or l.2Km to elapse before a repeater driver is required and four such repeater drivers can be used on any one bus 204. With the previous described system utilising mains signalling this was not possible. The electronics required to fit a repeater unit to amplify a mains borne carrier is too complex to be commercially viable. The present system therefore allows much greater flexibility. Further, the ability to use repeater units allows the remote stations 228 to be positioned at much greater distances from the base station than using the mains borne signalling embodiment (up to 6Km) .

Claims

59

1. A luminaire comprising a luminaire housing containing: a light source adapted, in use, to provide light, monitoring means adapted, in use, to monitor a physical parameter of the light source, and local processing means adapted to receive a parameter signal from the monitoring means indicative of said physical parameter and output an output signal, said output signal being adapted to be communicated to a remote unit, not part of said unit, which is remote from the housing; in which the monitoring means and the local processing means are provided in the housing, and the housing has mounting means adapted to mount it, in use, on a support; the luminaire having an electrical input/output coupling means adapted to be coupled to a power supply line, the luminaire receiving power for the light source via the electrical coupling means.

2. A luminaire according to claim 1 in which the mounting means comprises a neck portion of the housing adapted to be connected to the top of the lamp-post.

3. A luminaire according to claim 2 in which the electrical coupling means connects in use to the power supply line through the inside of the neck portion.

4. A luminaire according to any preceding claim in which the local processing means has a memory which stores data representative of the time the apparatus is operating, but not at least some other data that the local processing means monitors.

5. A luminaire according to any preceding claim in which the local processing means is adapted to transmit signals to the remote unit on an event driven basis, transmitting upon a predetermined change in the status of said parameter, or upon receipt of a communications request.

6. A luminaire according to any preceding claim in which the local processing means has an address which is hardware configurable.

7. A luminaire according to any preceding claim in which the local processing means is adapted to transmit data in short bursts repeated a plurality of times in different time domains.

8. A luminaire according to any preceding claim in which the local processing means is adapted to monitor continually the parameter status and to react to predetermined set points.

9. A luminaire according to any preceding claim in which the local processing means is adapted to operate from a low power supply.

10. A luminaire according to any preceding claim in which the local processing means is adapted to maintain data integrity by way of a multi-level (e.g. five level) pre-transmission/acceptance check before data transmission from the local processing means to the remote unit occurs.

11. A luminaire according to any preceding claim in which local processing means communication is half duplex, the local processing means having the ability to transmit or receive data, but not simultaneously.

12. A luminaire according to any preceding claim in which the local processing means is adapted to control loads from a remote command.

13. A luminaire according to any preceding claim in which the local processing means has the ability to take analogue signals direct from a mains power supply to said luminaire.

14. A luminaire according to any preceding claim in which the local processing means has the feature that the local processing means is adapted to communicate digital or analogue data up to a resolution of 10 bit with an accuracy of better than + or - 1% by way of conversion of a typical analogue to digital result into signal ASCII characters prior to transmission, digital interpretation taking place in the local processing means and being readable in plain English directly from the point of acquisition with no further requirement for de-coding or translation, the local processing means being adapted to be ported directly into proprietary software packaging.

15. A luminaire according to any preceding claim in which the local processing means only sends its signals to the remote unit when the remote unit is not being addressed by any other local processing means.

16. A luminaire according to any preceding claim in which the local processing means sends its signal to the remote unit at regular intervals, for example every hour or once a day.

17. A luminaire according to any preceding claim in which the local processing means (or the remote unit) polls the remote unit (or the local processing means) and transmits processed data signals only when a down loading signal is received.

18. A luminaire according to any preceding claim in which the local processing means (or the remote unit) stores data.

19. A luminaire according to claim 18 in which the local processing means monitors the monitoring means signals, but not record data on them (for onward transmission to the remote processor) unless they fall outside (or within) a predetermined range or value.

20. A luminaire according to claim 18 or claim 19 in which the local processing means (or the remote unit) records data indicative of the performance of a light source for only a predetermined time following start up of the light source.

21. A luminaire according to any preceding claim in which the local processing means processes a plurality of monitoring means signals that it receives and dependant upon these monitoring means signals the local processing means passes on appropriate signals to the remote unit.

22. A luminaire according to claim 21 in which the processing means processes a plurality of different physical parameters each of the physical parameters being represented by a separate signal from the monitoring means.

23. A luminaire according to any preceding claim in which the remote unit can be interrogated by a user.

24. A luminaire according to claim 23 in which the remote unit can be remotely interrogated by a user.

25. A luminaire according to any preceding claim in which the local processing means receives signals from the remote unit (and vice versa) via mains power supply cables of the light source.

26. A luminaire according to any preceding claim in which the local processing means operates a control unit to operate the light source.

27. A luminaire according to claim 26 in which the monitoring means monitors the voltage and current of the light source.

28. A luminaire according to any preceding claim in which the housing unit includes visual indication means adapted to produce a visual output signal representative of a physical parameter of the light source.

29. A luminaire according to claim 28 in which the visual indication means is adapted to indicate when the remote unit is communicating with the local processing means (or vice versa).

30. A luminaire according to any preceding claim in which the monitoring means is adapted to monitor the voltage at the light source before and/or after the light source is energised.

31. A luminaire according to any preceding claim in which the monitoring means is adapted to monitor the current flowing through the light source.

32. A luminaire according to any preceding claim in which the monitoring means is adapted, in use, to measure load currents in the range of 8w to 1.2kw.

33. A luminaire according to any preceding claim in which the light source has an operating voltage of between 80 and 260 volts A.C.

34. A luminaire according to any preceding claim which is provided with surge protection to B.S.I. class B (6kv 1.2 x 50µs).

35. A luminaire according to any preceding claim in which the frequency of a mains supply for the light source is substantially in the range of 45-65Hz.

36. A luminaire according to claim 35 in which the frequency of the mains supply for the electrical apparatus is substantially 50Hz.

37. A luminaire according to any preceding claim in which the local processing means is able to monitor the amount of time that the light source is operational.

38. A luminaire according to any preceding claim in which the local processing means is adapted, in use, to modulate the signal present on the mains power supply cables at a carrier frequency of substantially 135kHz.

39. A luminaire according to any preceding claim in which the remote unit and/or the local processing means incorporate phase locked loops.

40. A luminaire according to any preceding claim in which the local processing means is a microcontroller.

41. A luminaire according to claim 40 in which the microcontroller is encased in a matrix such as a resin block.

42. A luminaire according to any preceding claim in which the local processing means is provided with an identity code unit, the arrangement being such that the identity code unit can be removed from the local processing means and can be re-used with a new local processing means.

43. A luminaire according to claim 42 in which the identity code unit comprises a plurality of coupling members adapted to cooperate with a plurality of complementary coupling members provided on the local processing means, the arrangement being such that when the code unit is mounted on the local processing means electrical connection is made between certain complementary coupling members, dependant upon the configuration of the code unit.

44. A luminaire according to claim 43 in which the code unit has a plurality of wires linking parts of its coupling members.

45. A luminaire according to any preceding claim in which the remote unit is adapted in use to receive signals from a plurality of said local processing means.

46. A luminaire according to any preceding claim in which the housing unit is adapted, in use, to co-operate with a complementary mounting means.

47. A luminaire according to any one of claims 1 to 46 having an input to the control means, in use, of signals from a photodetector provided to sense whether a door at a base portion of a lamp-post is open or closed.

48. A method of providing a monitorable luminaire comprising providing a luminaire (housing unit) containing a light source, a local processing means, and a monitoring means, the monitoring means, in use, monitoring a physical parameter of the light source and generating a parameter signal representative of the physical parameter, the processing means receiving the parameter signal and outputting a processed parameter signal onto the power supply cables of the light source, in which the method comprises connecting the luminaire to an existing power supply cable and mounting means so providing a luminaire capable of being remotely monitored via the power supply cable to the light source by a remote unit which is remote from the luminaire.

49. A method of allowing remote monitoring of a light source according to claim 48 in which the local processing means monitors signals representative of said parameter, but does not store all of the data it is fed by the monitoring means, but does store at the local processing means data relating to the time that the light source has been operating.

50. A method according to claims 48 or 49 in which the local processing means transmits temporarily stored data to said remote unit on an event driven basis, transmitting upon a change of the monitored parameter, or upon a communications request from the remote unit.

51. A method according to any one of claims 48 to 50 in which the data transmission from the local processing means to the remote unit is sent in a plurality of short bursts in different time domain.

52. A method according to any one of claims 48 to 51 in which the local processing means continually monitors its own parameter status and reacts as its parameters reach or pass predetermined set points.

53. A method according to any one of claims 48 to 52 which ensures that the data stream received by the remote unit is at a predetermined rate.

any extra or non ASCII characters re-setting the receive buffer of the remote unit to zero and requiring repeat transmission.

54. A method according to any one of claims 48 to 53 wherein the local processing means and remote unit communicate digital, or analogue data up to a resolution of 10 bit with an accuracy of better than + or - 1 % by way of conversion of a typical A to D result into single ASCII characters prior to transmission, digital interpretation taking place in the local processing means and being capable of being read in plain English directly from the point of acquisition with no further requirement for decoding or translation, so that the data is adapted to be ported directly into proprietary software packaging.

55. A method according to any one of claims 48 to 54 in which the local processing means communicates with the remote unit using half duplex, each unit having the ability to transmit or receive data but not simultaneously allowing the local processing means to control loads from a remote command.

56. A method according to any one of claims 48 to 55 in which the local processing means provides an analogue R.M.S. reading of load current passing through said light source.

57. A method according to any one of claims 48 to 56 which comprises modifying the signal present on the mains power supply cables to allow the local processing means to communicate with the remote unit.

58. A method according to any one of claims 48 to 57 wherein a number of light sources are be monitored by a single remote unit.

59. A method according to claim 58 in which the local processing means of a first light source monitors the signal on the mains power supply cable to ensure the local processing means on a different (second) light source monitored by the same remote unit as the first light source is not communicating with the remote unit (or the remote unit is not communicating with the second light source) when the local processing means of the first light source communicates with the remote unit.

60. A method according to claims 58 or 59 which allows the remote unit to issue global commands which effect all local processing means and/or control means in communication with the remote unit.

61. A method according to any one of claims 58 to 60 wherein the remote unit issues commands which effect only specific local processing means and/or control means.

62. A method according to any one of claims 58 to 61 which comprises issuing commands from the remote unit which activate each of a plurality of the light source in communication with the remote unit in sequence.

63. A method according to any one of claims 58 to 62 which comprises adjusting a hardware configurable address to give each light source a unique address.

64. A method according to any one of claims 48 to 63 which comprises providing control means in the luminaire to operate the light source, which can be controlled by signals from the remote unit.

65. A method according to any one of claims 48 to 64 in which the remote unit issues commands to turn off (or reduce the current) to the light source at specific times.

66. A method according to any one of claims 48 to 65 in which the remote unit sounds an alarm when an error message is received from a local processing means.

67. A method according to any of claims 48 to 66 comprising fitting luminaires to lamp posts (or mounting means) already in situ.

68. A method according to any one of claims 48 to 67 in which the local processing means (or the remote unit) records data indicative of the performance of a light source for only a predetermined time following start up of the light source.

69. A method according to any one of claims 48 to 68 in which the local processing means processes a plurality of monitoring means' signals that it receives and dependent upon these monitoring means signals the local processing means passes on appropriate signals to the remote unit.

70. A method according to any one of claims 48 to 69 in which the processing means processes a plurality of different physical parameters each of the physical parameters being represented by a separate signal from the monitoring means.

71. A method according to any one of claims 48 to 70 in which the remote unit is remotely interrogated by a user.

72. A method according to any one of claims 48 to 71 which comprises providing the housing unit with a visual indication means adapted to produce a visual output signal representative of a physical parameter of the light source.

73. A method according to claim 72 in which the visual indication means indicates when the remote unit is communicating with the local processing means (or vice versa).

74. A method according to any one of claims 48 to 73 in which the monitoring means monitors the voltage at the light source before and/or after the light source is energised.

75. A method according to any one of claims 48 to 74 in which the monitoring means monitors current flowing through the light source.

76. A method according to any one of claims 48 to 75 in which the monitoring means measures load currents in the range of 8w to 1.2kw.

77. A method according to any one of claims 48 to 76 in which the light source operates at a voltage of between 80 and 260 volts A.C.

78. A method according to any one of claims 48 to 77 comprising providing the light source with surge protection to B.S.I. class B (6kv 1.2 x 50µs).

79. A method according to any one of claims 48 to 78 in which the frequency of a mains supply for the light source is substantially in the range of 45-65Hz.

80. A method according to any one of claims 48 to 79 in which the frequency of the mains supply for the electrical apparatus is substantially 50Hz.

81. A method according to any one of claims 48 to 80 in which the local processing means monitors the amount of time that the light source is operation.

82. A method according to any one of claims 48 to 81 in which the local processing means modulates the signal present on the mains power supply cables at a carrier frequency of substantially 135kHz.

83. A method according to any one of claims 48 to 82 wherein the local processing means transmits signals to the remote unit on an event driven basis, transmitting upon a predetermined change in the status of said parameter, or upon receipt of a communication request, to the local processing means.

84. A method according to any one of claims 48 to 83 in which the local processing means maintains data integrity by way of a multi-level pre-transmission/acceptance check before data transmission from the local processing means to the remote unit occurs.

85. A method according to any one of claims 48 to 84 in which an address of the processing means is manually configurable by a user at the site of the light source.

86. A method according to any of claims 48 to 85 in which the remote unit obtains data in the field from a plurality of local processing means', and has the ability to have data manually entered into it in the field, and has a visual display unit adapted to display information to a user, and maintains a log with data and time recorded for data transmitted to it from the local processing means'.

87. A method according to claim 86 in which the remote unit has built in software tools to process the data it receives.

88. A kit for connecting to a lamp post, the kit comprising a self-contained luminaire housing monitoring means capable of monitoring in use the operation of the lamp and communicating with a remote unit, the kit once connected being capable of performing the method of claims 48 to 87.

89. A method of providing a street with street lamps comprising performing the method of claims 48 to 88 to a number of lampposts (or monitoring means) already in situ.

90. A method of providing a monitorable street lamp substantially as described herein with reference to the accompanying drawings.

91. A kit for connecting to a lamp post substantially as described herein with reference to the accompanying drawings.

92. A method of providing a street with lamps substantially as described herein.

93. A kit for connecting to a lamp post, the kit comprising a self-contained luminaire monitoring means having a luminaire housing and a local processing unit provided with in the housing, and capable of monitoring in use the operation of the lamp and communicating with a remote unit, the luminaire being capable of being operated in accordance with any one of the method claims 48 to 90.

94. A method of providing a street with street lamps comprising fitting housing units according to any of claims 1 to 47 to lamp posts already in situ.

95. An item of street furniture comprising a post, or other support structure, and a luminaire in accordance with any of claims 1 to 47.

96. An item of street furniture according to claim 95 which is a street lamp.

97. A system comprising a plurality of street furniture having a luminaire in accordance with claims 1 to 47 and a remote unit adapted, in use, to receive signals from local processing means of said luminaire.

98. A system according to claim 97 in which the street furniture comprises lamp posts.

99. A system according to claim 97 or claim 98 which is adapted, in use, to control the operation of the light source of the items of street furniture.

100. A luminaire substantially as described herein with reference to the accompanying drawings.

101. A method of allowing remote monitoring of a light source substantially as described herein with reference to the accompanying drawings.

102. A kit for connecting top a lamp post substantially as described herein with reference to the accompanying drawings.

103. A method of providing a street with street lamps substantially as described herein with reference to the accompanying drawings.

104. An item of street furniture substantially as described herein with reference to the accompanying drawings.

105. A system substantially as described herein with reference to the accompanying drawings.

106. An item of street furniture substantially as described herein with reference to the accompanying drawings.

107. A system substantially as described herein with reference to the accompanying drawings.

108. Monitoring apparatus adapted, in use, to monitor a light source substantially as described herein with reference to the accompanying drawings.

109. A method of remote monitoring of a light source substantially as described herein with reference to the accompany drawings.

110. A network of light sources substantially as described herein with reference to the accompanying drawings.

111. A method of providing a monitorable luminaire comprising providing a luminaire (housing unit) containing a light source, a local processing means, and a monitoring means, the monitoring means, m use, monitoring a physical parameter of the light source and generating a parameter signal representative of the physical parameter, the processing means receiving the parameter signal and outputting a processed parameter signal to be detected by a remote unit, in which the method comprises connecting the luminaire to an existing power supply cable and mounting means so providing a luminaire capable of being remotely monitored by a remote unit which is remote from the luminaire.

112. A system capable of monitoring and controlling a number of pieces of electrical apparatus within a region, the system comprising a base station capable of communicating with at least one remote station, via a communication medium, each remote station being associated with at least one piece of electrical apparatus and further each remote station comprising a local processing means capable of communicating with the base station, a monitoring means capable of monitoring a parameter of the electrical apparatus and producing an output signal representative of the parameter and communicating the output signal to the local processing means and a control means capable of controlling the electrical apparatus upon receipt of signals from the local processing means wherein the communication medium is a bus linking at least one remote station to the base station.

113. A system according to claim 112 wherein a housing unit is provided which contains as least a single piece of electrical apparatus and the remote station.

114. A system according to claim 113 wherein the housing unit contains a number of pieces of electrical apparatus which are adapted to be monitored and controlled by the remote station within that housing.

115. A system according to any one of claims 112 to 114 wherein the electrical apparatus comprises a light source, adapted in use to provide light.

116. A system according to any one of claims 112 to 115 wherein the remote station (or the base station) are adapted to compensate for the failure of a piece of electrical apparatus by utilising a second different piece of apparatus in its place.

117. A system according to claim 116 wherein the remote station (or base station) is adapted to compensate for light source failures within a particular housing.

118. A system according to any claim directly or indirectly dependent from claim 114 wherein for each housing unit there is run only a live, neutral, earth and bus wires.

119. A system according to any one of claims 112 to 118 wherein the base station polls the remote stations.

120. A system according to claim 119 wherein the base station polls the remote stations in a pre-set sequence.

121. A system according to claim 120 wherein an interrupting means is provided which is adapted to interrupt the pre-set sequence of polling of the remote stations.

122. A system according to claim 121 wherein the interrupting means comprises a control station which is adapted to send commands from a location remote from the base station and remote station.

123. A system according to claim 122 wherein the control station is adapted to cause the base station to issue commands affecting electrical apparatus connected to the system.

124. A system according to claim 123 wherein the base station is adapted to resume its pre-set polling sequence from the remote station it was caused to process during a command from the interrupting means.

125. A system according to any one of claims 112 to 124 which is adapted to control an area illuminated by a number of light sources.

126. A system according to claim 125 wherein the system is adapted to illuminate the area according to a number of pre-set lighting levels.

127. A system according to claim 126 as it depends directly or indirectly from claim 121 which is adapted to allow the light sources to be stepped through the pre-set levels of illumination by inputting of commands to the interruption means.

128. A system according to any claim directly or indirectly dependent upon claim 115 wherein the monitoring means is adapted, in use, to monitor the light intensity output from the light source.

129. A system according to claim 128 wherein a light intensity detector is provided in the vicinity of the light source and is adapted to monitor the light intensity output from the light source.

130. A system according to claim 128 wherein an end portion of a fibre optic cable is provided in the vicinity of the light source and is adapted to transmit the light output from the light source to a light intensity detector.

131. A system according to any one of claims 112 to 130 wherein the bus operates at a frequency of substantially 19.2 baud.

132. A system according to any one of claims 112 to 131 wherein the base station is adapted, in use, to poll the remote stations at a rate of substantially 1 per second.

133. A system according to any one of claims 112 to 132 wherein the local processing means (or base station) is adapted, in use, to store data on signals if predetermined criteria are met by the data.

134. A system according to claim 133 wherein the local processing means could be set up to ignore signals that are at substantially the normal level, or within an allowable deviation of normal.

135. A system according to any claim directly or indirectly dependent upon claim 113 wherein the housing unit is a luminaire.

136. A system according any claim directly or indirectly dependent upon claim 113 wherein the housing unit includes a visual indicating means adapted to produce a visual output signal representative of a physical parameter of the electrical apparatus.

137. A system according to claim 136 wherein the visual indicating means comprises an LED which is illuminated when the electrical apparatus should be on.

138. A system according to claim 136 wherein the visual indicating means is adapted to indicate when the base station is communicating with the local processing means or remote station (or vice versa).

139. A system according to any one of claims 112 to 138 wherein the local processing means or the remote unit may be able to monitor the time the light source is on; that is emitting light.

140. A system according to any one of claims 112 to 139 wherein the base station is provided with a memory means wherein the memory means are adapted to record signals sent to the base station from the local processing means.

141. A system according to any one of claims 112 to 140 wherein the local processing means is a microcontroller.

142. A system according to any one of claims 112 to 141 wherein the address of each of the remote stations (as recognised by the base station) is hardware configurable.

143. A system according to claim 142 wherein the remote station is provided with switches which can be configured to give the correct address.

144. A system according to any claim directly or indirectly dependent upon claim 113 wherein the housing unit comprises connection means adapted, in use, to co-operate with a complementary mounting means.

145. A system according to claim 144 wherein electrical coupling means are provided which are adapted to be connected to an electrical supply means of the complementary mounting means.

146. A system according to claim 145 wherein the electrical coupling means include a connection for the bus so that the bus is connected as the electrical coupling means are connected.

147. A system according to any one of claims 112 to 146 wherein the local processing means has a memory which stores data representative of the time the apparatus is operating.

148. A method of remote monitoring and controlling of at least one piece of electrical apparatus, comprising providing a base station and at least one remote station associated with a piece of electrical apparatus, communicating with the remote station via a communication medium wherein each remote station is provided with a monitoring means adapted to monitor a parameter of the electrical apparatus and a control means adapted to control the apparatus and wherein the communication medium is a bus.

149. A method according to claim 148 wherein the monitoring means monitors signals representative of a parameter of the electrical apparatus, processes those signals and outputs an output signal to the local processing means.

150. A method according to claim 148 or 149 comprising placing the remote station within a housing of the electrical apparatus.

151. A method according to any one of claims 148 to 150 which is applied to light sources.

152. A method according to claim 151 comprising monitoring, remotely, street furniture, perhaps street lamps.

153. A method according to claim 152 wherein tunnel lights are monitored.

154. A method according to any claim directly or indirectly dependent upon claim 150 comprising connecting the housing means of the electrical apparatus to mounting means (e.g. lamp posts) which have already been provided.

155. A method according to claim 154 comprising providing a housing unit which simply needs to be connected to mains power supply cables and bus cable in order to provide a working electrical apparatus with the ability to be remotely monitored.

156. A method according to any one of claims 148 to 155 comprising monitoring a number of electrical apparatus by a single remote station.

157. A method according to any one of claims 148 to 156 comprising causing the base station to issue commands to the local processing means causing the control means to operate the electrical apparatus.

158. A method according to any one of claims 148 to 157 comprising issuing commands from the base station which activate the electrical apparatus in communication with the base station in sequence.

159. A method according to any one of claims 148 to 158 comprising issuing commands from the base station to turn off (or reduce the current to) electrical apparatus at specific times.

160. A method according to any one of claims 148 to 159 comprising causing remote stations connected the base stations to compensate for failure of a first piece of electrical apparatus by utilising a second different piece of apparatus.

161. A method according to any one of claims 148 to 160 comprising wiring a luminaire containing a plurality of electrical apparatus with only a live, neutral, earth and bus wires.

162. A method according to any one of claims 148 to 161 comprising polling each of the remote stations with the base station.

163. A method according to claim 162 comprising polling the remote stations in a pre-set sequence.

164. A method according to claim 162 or 163 comprising providing an interrupting means allowing the pre-set sequence of remote station polling to be interrupted.

165. A kit adapted to connect to a luminaire mounting means, the kit comprising a self-contained luminaire housing monitoring means capable of monitoring in use the operation of a light source and communicating with a base station.

166. A method of providing a street with street lamps comprising fitting the system of any one of claims 112 to 147 to existing mounting means adapted to support luminaires.

167. An item of street furniture (for example a lamp post) comprising a post, or other support structure, and a housing unit, or luminaire, in accordance with any one of claims 112 to 147.

168. Monitoring apparatus adapted to monitor electrical apparatus comprising a sensor to monitor a parameter of the electrical apparatus, a local processing means and a base station geographically separate from the electrical apparatus in which the local processing unit is adapted to process signals from the sensor and transmit its own signals to the base station.

169. A method of remote monitoring of an electrical apparatus, the method comprising providing a sensor to monitor a parameter of the electrical apparatus, providing a base station geographically separate from the electrical apparatus, at which a user can obtain information about the electrical apparatus, and further comprising providing a local processing means at the electrical apparatus, the local processing means processing the signals from the sensor before it transmits its own signals to the base station.

170. A system substantially as described herein with reference to the accompanying drawings.

171. A method of remote monitoring and controlling of at least one piece of electrical apparatus substantially as described herein with reference to the accompanying drawings.

172. A kit substantially as described herein with reference to the accompanying drawings.

173. A method of providing a street with street lamps substantially as described herein with reference to the accompanying drawings.

174. An item of street furniture substantially as described herein with reference to the accompanying drawings.

175. Monitoring apparatus adapted to monitor electrical apparatus substantially as described herein with reference to the accompanying drawings.