WO2000043966A1

WO2000043966A1 - Improvements in and relating to remote monitoring and signalling, especially in tunnels

Info

Publication number: WO2000043966A1
Application number: PCT/GB2000/000126
Authority: WO
Inventors: Raymond Mew; Jeanette Mew
Original assignee: Raymond Mew; Jeanette Mew
Priority date: 1999-01-20
Filing date: 2000-01-20
Publication date: 2000-07-27
Also published as: GB2345998A; GB9901173D0; AU3062900A

Abstract

A system capable of monitoring and controlling a number of pieces of electrical apparatus (16, 18, 20, 22, 24, 26) within a region, the system comprising a base station (2) capable of communicating with at least one remote station (28), via a communication medium, each remote station (28) being associated with at least one piece of electrical apparatus (16, 18, 20, 22, 24, 26) and further each remote station (28) comprising a local processing means capable of communicating with the base station (2), 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 (16, 18, 20, 22, 24, 26) upon receipt of signals from the local processing means wherein the communication medium is a bus (4) linking at least one remote station to the base station. This system is especially suitable for monitoring and controlling lighting within a tunnel. However, the system is capable of providing full environmental control within the tunnel.

Description

IMPROVEMENTS IN AND RELATING TO REMOTE MONITORING

AND SIGNALLING, ESPECIALLY IN TUNNELS

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, and one embodiment is especially adapted for tunnels, and areas where there is a confined space, or where it is desirable to reduce wiring.

Methods and apparatus for monitoring and controlling the function of electrical apparatus (in particular but not exclusively street furniture) are disclosed in our prior applications GB 2 291 993 and WO 98/02859.

According to a first 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.

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. 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 be described in relation to controlling lighting (and other electrical apparatus) within a tunnel, hereinafter referred to as street lighting. The skilled person will appreciate that the invention has wider applications. Indeed the application of the invention to street furniture in general will be apparent from our earlier applications whose numbers are quoted above. 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 be a light source, adapted in use to provide light. The housing unit may be a luminaire (light unit) . Alternatively, the electrical apparatus may well be a motor, a fan, a pump or indeed any piece of monitorable and/ or controllable electrical apparatus.

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 may 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 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 its supporting structure in any case, and it costs no more, or little extra, in installation time to install a self-checking luminaire than a standard one.

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 first 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 (the switch gear can be housed in a smaller and cheaper building if it is itself smaller) .

Data transmission from the local processing means to the base station may be on an event driven basis or in the preferred embodiment data transmission from the local processing means (or the remote station in general) to the base station occurs when the base station 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 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 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 polls may be substantially any of the following: 0.1s, 0.5s, Is, 5s, 10s, 30s or 60s.

Interrupting means may be provided which is adapted to interrupt the preset sequence of polling of the remote stations. This allows the base 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 are 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. The control centre may have a display showing pictures, preferably real time, of the tunnel (or different parts of the tunnel, possibly of different parts of the tunnel at different times) . Thus a control operator can visually check from a picture on a monitor what the light level is/see what is happening.

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 capability of controlling a number of pieces of apparatus was not possible with the system described in our earlier applications. For example, a single remote station is adapted to control a number, perhaps six, light sources within a particular housing. This may increase the number of pieces of electrical apparatus that the system can control. Each piece of electrical apparatus may be identified as a sub-address of the address of the remote station, e.g. light three of remote station sixty.

If the pieces of electrical apparatus are light sources, they may be of different light outputs, allowing more lighting levels to be achieved than the number of sources within the housing.

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 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 along the length of the tunnel is then tailored so that the light level is reduced as one progresses further into the tunnel 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. The base station may have an input informing it of external conditions. For example it may be informed of the brightness of daylight, whether it is raining, of the pollution level, etc.

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. There may however be any number of lighting levels, perhaps 2,3,4,5,7,8,9,10, etc.

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. This would provide local intelligence within the luminaire and distribute the processing power through the system.

Sensors may 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. Indeed, the sensors may be able to count the number of vehicles passing the sensor. This information may be useful for statistical purposes.

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.

The local processing means may be arranged so that it monitors signals from the monitoring means continuously or at predetermined times. The local processing means (or base station) 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 base station. For example, in lamp posts (or indeed tunnel lights) most lamp failures occur in the first 30 minutes following start up of the lamp. The local processing means (or the base station) 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 the monitoring means signals, but not record data on them (for onward transmission to the base station) unless they fall outside (or within) a predetermined range or value. Alternatively, the base station may receive signals but not record them if they are outside (or within) a predetermined range or value.

For example, a lamp post (or tunnel light) 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, 5N ± 0.5N (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 base station. Instead of waiting for its normal poll from the base station it would be possible for the local processing means to poll the base station as soon as an unacceptable signal has been received, or when it determines that the out-of-range sensor signal is not a reading error (i.e. the local processing means could potentially act as a interrupting means). However, this is not the preferred embodiment and its is preferred to simply let the base station poll the local processing means and process the errors as and when it reads them from the local processing means.

Each remote station may comprise a number of monitoring means. Preferably the monitoring means allow the local processing means of the remote station to 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; f) the light level being emitted from a light source; or g) any combination of a) to f).

For example when the electrical apparatus is a light source 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 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 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 is adapted to monitor the light intensity output from the light source. This is advantageous because the I vs. N 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 put 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 device 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 device may be a photodiode. The fibre optic cable may be a polymer light guide. The light intensity monitoring device may be provided as a component of a luminaire, or attached to or associated with a luminaire.

The base station may be interrogated by a user, preferably remotely interrogated.

The local processing means may operate a control unit to operate the electrical apparatus, perhaps between an on and an off state. This may be in response to signals transmitted down the communication medium or may be as a result of the program operating on the local processing means. This has the advantage that it allows the local processing means to monitor the operation of the electrical apparatus and send signals back to the base station to indicate a fault. It has the further advantage that the base station can send signals to the local processing means, and perhaps control the operation of the electrical apparatus.

If the electrical apparatus is a light source it 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 base station to the various physical parameters being monitored.

The electrical apparatus may comprise a housing unit in which the remote station is provided. Therefore, the monitoring means, the control means and the local processing may be provided within the housing unit. For example when the electrical apparatus is a light source the luminaire for the light source may comprise the housing and the remote station may be provided within the housing unit.

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 electrical apparatus. For example, the visual indicating means may comprise an LED which is illuminated when the electrical apparatus 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 base station is communicating with the local processing means or remote station (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.

Preferably the monitoring means adapted to monitor current can measure load currents in the range 8w to 1.2kw. 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 50μs). 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.

It may 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 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 base station may be provided with a memory means. The memory means may record signals sent to the base station 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 local processing means may have a memory.

The memory of the local processing 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.

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.

Preferably the address of each of the remote station (as recognised by the base station) is hardware configurable.

This enables us to make all of the remote stations identical, without the need to give them an identity code. This reduces their unit cost. Furthermore, since the remote stations are identical if one fails on-site an engineer can carry a spare remote station with them to the electrical apparatus and can replace it there and then simply reconfiguring the address to allow it to work with the system.

The remote station may be 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 remote station.

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. The code unit may be considered to be a coding key. In another 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 10 wires linking 10 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. 2,3,4,5,8,9 and 10 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 base station may be adapted to receive signals from a plurality of remote stations.

Preferably the housing unit comprises connection means 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.

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. Electrical coupling means may be provided for the bus so that the bus is connected as the electrical coupling means are connected.

The local processing means may have a memory which stores data representative of the time the apparatus is operating, but may store some other data that the local processing means monitors.

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.

The local processing means may be adapted to operate from a low power supply. The local processing means may communicate in half or full duplex, the local processing means having the ability to transmit and receive data simultaneously if desired.

Preferably the local processing means unit is adapted to control loads from a remote command.

The local processing means may also have 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 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.

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 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.

According to a second 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 monitoring means may monitor signals representative of a parameter of the electrical apparatus, process those signals and output an output signal to the local processing means. The local processing means may not store all of the data it is fed by the monitoring means, but may store at the local processing means data relating to the time that the electrical apparatus has been operating.

The local processing means may continually monitor its own parameter status and react as its parameters reach or pass predetermined set point.

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 and the local processing means (which are part of the remote station) . The electrical apparatus may be a light source adapted, in use, to produce light. The housing may be a luminaire.

Preferably the method is a way of monitoring, remotely, street furniture, perhaps street lamps. The street lamps may be tunnel lights. Further, the method may be a way of monitoring, or controlling, the environment within an area. The environment may be controlled by controlling electrical apparatus such as fans, air conditioning, etc.

The method may comprise 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 communication medium may be connected as the housing means is connected to the mounting means.

The method may further comprise 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. Not only may such a method provide a cheap efficient way of providing an electrical apparatus which can be remotely monitored, in the case of street lamps 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 10m above street level).

The method may allow a number of electrical apparatus to be monitored by a single remote station. This has the advantage that it is much more efficient than providing a single remote station 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 base station. This may provide a simple way to provide communication.

The base station 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. Global commands may be issued which effect all remote stations connected to the base station.

Alternatively or additionally the base station 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 base station which activate the electrical apparatus in communication with the base station 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 base station may issue commands to turn off (or reduce the current to) electrical apparatus at specific times. An advantage of this is that energy consumption may be reduced.

The base station 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.

Preferably the method comprises 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. This may make the are 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 stations may be polled in a pre-set sequence.

According to a third aspect of the invention we provide a kit for connecting 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.

According to a fourth aspect of the invention we provide a method of providing a street with street lamps comprising fitting the system of the first aspect of the invention to existing mounting means adapted to support luminaires.

According to a fifth aspect of the invention we provide an item of street furniture (for example a lamp post) comprising a post, mounting bracket, 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 monitoring apparatus for monitoring 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.

According to an seventh 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 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.

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.

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 cabling, radio links, etc.) .

According to a further aspect of the invention there is provided an environmental control system.

Preferably the system is adapted to control the environment within a tunnel, possibly a road or street tunnel.

Such a system may control lights, fans, pumps, traffic control devices, emergency lighting, cameras, etc.

According to a further aspect of the invention there is provided a method of controlling the environment.

Preferably the method controls the environment within a tunnel.

According to a further aspect of the invention there is provided a method of reducing the wiring in a monitored/controlled environment. The environment may be a tunnel.

Embodiments of the invention will now be 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 pieces of electrical apparatus;

Figure 2 shows a schematic view of the wiring requirements for a lighting source according to the prior art; Figure 3 shows an identity code key which may be used to provide an address for each of the remote stations;

Figure 4 shows a monitoring system;

Figure 5 shows a schematic of a light unit in accordance with the invention; and

Figure 6 shows an isometric view of a housing means suitable for use with a street lamp.

The system of Figure 1 comprises a base station 2 connected via an RS458 bus 4 to a plurality of electrical apparatus 6, 8, 10, 12 and control station 14. In the embodiment shown, each of the electrical apparatus comprises a luminaire containing a number of light sources.

Each of the luminaires shown is identical, but the skilled person will appreciate that the luminaires connected to the base station 2 could each be different. Indeed pieces of electrical apparatus other than luminaires and light sources may be connected to the base station 2.

Each luminaire shown contains six separate light sources, two fluorescent tubes 16, 18 and four halogen bulbs 20, 22, 24, 26 (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 28 which contains a local processing means, a monitoring means and a control means. The local processing means can communicate with the base station 2 via the bus 4 and receive and send signals to the monitoring and control means respectively. Each luminaire receives a single phase of a three phase power supply 30, 32, 34, together with a neutral cable. There are therefore four wires going to each luminaire, a live 30, 32, 34, a neutral, an earth and a bus 4.

The base station 2 is a fully functioning computer built into a dedicated housing. On the front panel there is a display 36, a keyboard 38, status lights (mains 40, power supply (UPS) 42, + 12VDC 44, + 5NDC 46), a shielded reset button 48, a COM 1 port 50 (for external communication), a printer port 52, a joystick 54 and two input buttons 56, 58. The control station 14 has various features on its front panel: power supply status light 60, LED showing remote reset to automatic 62, an LED showing automatic running 64, an LED showing manual override occurring 66, a button for requesting automatic 68, a button for requesting manual 70, an eight segment display 72 and two input buttons 74, 76.

In use, a program is run on the base station 2 which continually polls each of the items of electrical apparatus 6, 8, 10, 12 connected to the bus 4. This polling occurs substantially every second and occurs is pre-set order (for instance luminaire 6, 8, 10, 12, etc.) . As commands are input to the base station 2 signals are sent down the bus 4 instructing various functions of the electrical apparatus. For instance light sources could be turned on or off, or a fan motor turned on, etc., data is sent back relating to the status of the piece of electrical apparatus.

Each remote station 28 communicating on the bus has an address which can be set by DIL switches. To communicate with a particular electrical apparatus the base station 2 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 28) will then cause the control means to alter the electrical apparatus as desired or send back information from the monitoring means. During the polling sequence the status of the electrical apparatus is sent back to the base by each remote station 28. 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 2 as and when required by the issue of an appropriate signal sent across the bus 4. 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 2 is in communication has the same arrangement of light sources 16, 18, 20, 22, 24, 26 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.

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.

The base station 2 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 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 possibly the base station 2) 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 14 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 66. 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 14 to the control station 14. An operator can use the buttons 74, 76 to step through the various lighting levels and the current level is displayed on the display 72.

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 66 and then step the lighting up to the required level. These inputs to the buttons 74, 76 are sent via the bus 4 to the base station 2 which in turn will pause its polling duties and send the relevant signals to the required remote stations.

Once the manual commands have been performed the base station starts its polling sequence again. However, to make the process more streamlined the base station 2 starts to poll the remote stations 28 from where it finished servicing the manual commands. For example if the base station 2 had been polling the remote station 28 of the luminaire 6 when a manual request was received which affected luminaire 10, the base station 2 would process the manual request and then return to its polling routine. However, rather than returning to poll the remote station 28 of luminaire 8 (the luminaire after luminaire 6) it would poll the remote station 28 of luminaire 12. The differences between the wiring systems of Figures 1 and 2 will be apparent. Figure 2 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 16, 18, 20, 22, 24, 26 has a live and a neutral cable run to it from a remote switch gear provided in switch gear room 78. These wires are too numerous to show individually and have been represented by the bundles 80, 82, 84, 86. 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 28.

Each luminaire can contain any number of light sources associated with a single remote station 28. 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 luminaire 88 (or housing means) is shown in more detail in Figures 5 and 6. The housing means 88 comprises a light source 90 and associated starter circuit 92, a monitoring means 94 and control means 96. A local processing means 98 is also provided. The housing means 88 contains all the necessary apparatus for running the light source 90 contained within. The monitoring means 94 comprises a plurality of sensors.

The base station 2 may contain, or have connected to it, a photocell which measures when the light sources need to be turned on, or alternatively, a control signal can be issued to turn the light sources on. In either case, when the light sources are required to be turned on, the base station 2 issues a light source 16, 18, 20, 22, 24, 26, 90 "on" signal to the local processing means 98 at luminaire 6, 8, 10, 12 . This is done in sequence as the base station polls each luminaire 6, 8, 10, 12 and helps to avoid a large spike being generated (as would happen if all of the light sources came on together). The local processing means 98 and the control means 96 at each luminaire 6, 8, 10, 12 will then switch the light source on. A predetermined period is allowed to elapse, say ten minutes, in order to allow the light source 16, 18, 20, 22, 24, 26 to warm up to its correct operating temperature. Once this time has elapsed, the processing means 98 at each luminaire 6, 8, 10, 12 then sends further signals back over the bus as the base station 2 polls the remote station 2. The signals are obtained by processing parameter signals generated by the monitoring means 94. The monitoring means 94 are adapted to measure the actual physical status of the lamp. 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 than trying to determine whether the light source is operating correctly by measuring the current. The I Ns N 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 16, 18, 20, 22, 24, 26, 90 is on, and has reached equilibrium (i.e. the parameters do not fluctuate substantially) the local processing means 98 sends a signal back to the base station 2 when the remote station is next polled in the event that one of the parameters changes. This may indicate that a fault has occurred in the light source 16, 18, 20, 22, 24, 26, 90.

The housing means may also incorporate means (perhaps the control means) for controlling the light output. This may then switch the light source 16, 18, 20, 22, 24, 26, 90 between full output and a dimmer output in response to a signal sent from the base station 2 to the local processing means 98. 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 light sources are provided. We may for example want to turn lights to their dim setting after a watershed time at night (e.g. 1.00am).

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 lighting level is increased, but during periods of low density the lighting level can be safely reduced.

Because each luminaire 6, 8, 10, 12 is individually controlled by the base station 2, it is possible to selectively dim one or more of a set of light sources within the luminaires 6, 8, 10, 12 or even selectively turn some off.

A signal from a remote station 28 is only logged by the base station 2 if it is an error signal. One particular case of interest is when a light source 16, 18, 20, 22, 24, 26, 90 continually switches between an ON and an on OFF state. This may occur if there is a fault in the light source 16, 18, 20, 22, 24, 26, 90 . In this case, it is possible to cause the local processing means 98 in the housing means to monitor the fault signal, and if more than a given number of fault signals occur within a predetermined period of time, the local processing means 98 may send an error signal to the base station 2 and shut down the particular, faulty, light source 16, 18, 20, 22, 24, 26, 90 until it is repaired. As discussed hereinbefore other light sources may be activated to compensate for the loss of light.

The signals sent back to the base station 2 provide for many possible improvements over the prior art method of monitoring street lamps. For example, the local processing means 98 may send a signal to the base station 2 indicating when a light source 16, 18, 20, 22, 24, 26, 90 actually turns on and when it actually turns off. The amount of time that a light source 16, 18, 20, 22, 24, 26, 90 is on is then recorded, and a cumulative total can be built up which is representative of the "burn time" of the light source 16, 18, 20, 22, 24, 26, 90. This is only possible by using the monitoring means which measures the actual amount of time a light source 16, 18, 20, 22, 24, 26, 90 is on, as distinct from the amount of time a light source 16, 18, 20, 22, 24, 26, 90 is instructed to be on. Obviously, the control means 96 in the housing means may have switched a light source 16, 18, 20, 22, 24, 26, 90 on, but if the light source 16, 18, 20, 22, 24, 26, 90 is not monitored to check that it is operating, a correct check of light source 16, 18, 20, 22, 24, 26, 90 "burn time" cannot be made.

By monitoring the actual "burn time" of the light source 16, 18, 20, 22, 24, 26, 90 before failure, lighting providers can then ask for a refund or may complain if a light source 16, 18, 20, 22, 24, 26, 90 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.

The system may be set up to monitor the burn time of each individual source within a luminaire and may be able to select which light sources should be "on" based upon the length of time the sources within the luminaire have been on already. This has the advantage that it can cause the sources to expire at roughly the same time, allowing them to be changed in one visit rather than several visits to the luminaire. Alternatively, the system may ensure that bulbs do not expire at the same time to reduce the dangers of having too many sources failing at once.

Control is provided for individual light sources. Effectively each light source within a luminaire may become a sub-address of the remote station within the luminaire (e.g. luminaire eight, light source three). To meet safety codes, light sources 16, 18, 20, 22, 24, 26, 90 at major junctions and roundabouts must be fully illuminated at all times (this is in the field of street lighting in general rather than tunnel lighting) . However, it is desirable to dim light sources 16, 18, 20, 22, 24, 26, 90 during periods of low road use to reduce power consumption (e.g. after midnight). Using this control method, a base station 2 may switch some light sources 16, 18, 20, 22, 24, 26, 90 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 100,102,104. The LED's 100,102,104 are illuminated in response to the output signals from the local processing means 98 provided with the housing means, or may be operated by sensors remote from the housing means. A first LED 100 shows that the light source contactors are switched ON, the second LED 102 shows that the light source is dimmed, and the third LED 102 shows that the light source is fully on. The LED's 100, 102, 104 can be used by maintenance staff to determine if the light source 16, 18, 20, 22, 24, 26, 90 is operating correctly.

A number of diagnostic tools may also be provided with this street lamp monitoring (or tunnel lighting) system. The base station 2 may send a test signal to the local processing means 98 as it polls that particular remote station, and the local processing means 98 may also be adapted to send a status check signal back to the base station 2 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 light source 16, 18, 20, 22, 24, 26, 90 in real time provides several additional operational advantages. Because the base station 2 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 luminaires 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 98 at the luminaire will send a signal back to the base station 2 (when it is polled) indicating that the luminaire 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 the base station 2 and a control centre elsewhere. This may be via a modem so that an operator can interrogate the data logged at the base station 2 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 luminaire 6, 8, 10, 12. Importantly, the housing means is self contained and incorporates its own monitoring means 94. This monitoring means 94 senses a parameter such as the current, voltage or light intensity at the light and may sense when a fault occurs. There may also be provided all the control means 96 and local processing means 98 required to implement a complete remote luminaire 6, 8, 10, 12 monitoring system suitable for remote interrogation over a communication medium. 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 and greatly reduces the amount of wiring which is required to implement a lighting system.

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 a communication medium, and mounted in an appropriate manner, to provide a working item of street furniture.

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 an electricity supply connected, and a bus connected. The system may provide a luminaire that simply needs connecting to a power supply and a bus. Therefore, an installer may connect the luminaire to a tunnel, connect the necessary cables and have a monitorable/controllable luminaire. Sensors may be provided wherein to monitor other aspects of the tunnel, for instance, air quality (and thus, control fans, etc.) traffic flow, etc. If the luminaire is the last on the bus, the user may simply move a provided bus termination into place.

The address of each remote station can be set by DIL switches (not shown). However, the skilled person will appreciate that there are other possibilities. For instance a removable code key as shown in Figure 3 is a possibility. The code key 106 is removable from the remote station and has 20 pins (10 sets of pairs) which are received in complementary holes provided in the circuit board of the remote station 28. The key 106 has 10 slots 108 in its back to enable a thin tool to be inserted into the slots 108. Behind the slots 108 are, in its original, unencoded state, respective wires 110 linking pairs of pins 112. The key 106 is encoded by breaking, or not breaking, particular wires by pushing the tool through the slots 108. In Figure 3 starting from the top, wires 1,5,7,8 and 10 have been broken, leaving wires 2,3,4,6 and 9 intact which provides the key 106 with a binary code (in this example 10 bit). Each local processing means would have its own, individual, and unique, coded key. It will be appreciated with an 10 bit key code we can handle 1024 units on a single bus. This could easily be upgraded by adding two or more bits. Instead of breaking wires on an identity key the user may manipulate switches to give it an identity.

The skilled person will appreciate that with each remote station 28 being able to control a number of light sources 16, 18, 20, 22, 24, 26, 90 a single base station 2 can control many thousands of light sources. Using our presently preferred number of six light sources per remote station 28 this gives 6144 light sources per bus 4. (Although the skilled person will realise this is above the number of address available from a 10 bit address). It is possible that a single remote station 2 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. This is a vast improvement upon the system disclosed in the earlier patents disclosed herein.

The bus 4 used in one embodiment (the RS485) allows 255 remote units 28 or 1.2Km to elapse before a repeater driver is required and four such repeater drivers can be used on any one bus 4. With the previous system disclosed in the patent application WO98/02859 this was not possible. The electronics required to fit a repeater unit to amplify a mains borne carrier was 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 28 to be positioned at much greater distances from the base station than in the system disclosed in WO98/02859 (up to 6Km).

The individual local processing means 98 provided in the luminaires 6, 8, 10, 12 are also programmed by the base station 2 to keep a record of any signals which are outside of an allowable range. Signals SI to S3 from three separate monitoring means are recorded as a matter of course in the memory of the local processing means 98 for the first 30 minutes, and not thereafter (as a matter of course), the local processing means 98 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 local processing means 98 may also be set up to transmit such unusual signals to the base station 2 when remote station 28 is polled.

It will be appreciated that the base station 2 could be arranged to vary the operational conduct of the local processing means 98, for example, the base station 2 could be used to tell the remote stations 28 to change the period of sampling of the monitoring means 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 local processing means 17 (which may be a microcontroller) is a powerful tool it can simply be reprogrammed once by the base station 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 98, the volume of signal traffic to the base station 2 is kept low.

It will be appreciated that one of the benefits of the present system is that each of the remote stations is identical (or substantially identical). This means that we can mass produce remote stations and use some and store some conveniently. If there is then a problem with one of the remote stations 28 an engineer can take a replacement from our store and visit the electrical apparatus that is having trouble (as detected by the base station 2). The engineer can replace the faulty remote station 28 and reconfigure the hardware address by use of the DIL switches or replace the key 106. This will guarantee that the remote station 28 will have the same address and the base station 2 will be able to correlate incoming signals with a particular piece of electrical apparatus. This avoids the need to have special programming of replacement chips, and reduces the down time involved in maintaining the system. 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 remote station 28. For example, we could have a plug-in filter unit to improve the noise filtering.

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, small enough for it to be fitted into the standard housing of a street lamp light source.

Figure 4 shows an embodiment of a monitoring system represented in a block diagrammatic form. A computer 200 running the system has dedicated software for data analysis and control. The computer 200 is connected to a monitor 202 by means of a communication link 206. Block 74 represents the local processing means or microcontroller. The communications link is a bus running under the RS485 protocol, a four wire bus, allowing full duplex communication to occur between the local processing means and the base station 2 (or computer 200) .

The monitor 202 is provided with an independent power supply 208, which is conveniently a mains supply with a transformer being provided to power the monitor 202. The microcontroller 210 (local processing means) is fed with information concerning the operation of a piece of electrical apparatus through a number of analogue inputs. There may be eight analogue inputs although only four inputs 212,214,216,218 are shown in Figure 4. Each input 212,214,216,218 is provided with a signal conditioner 222 and an opto-isolator 224. 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 222 scale the signal up or down to be in a range suitable for the microcontroller 210 to receive. This would be, for example, in the range 0-5 V. The opto-isolators 224 provide a potential cut out in case of power surges or other signals which can harm the microcontroller 210.

The microcontroller 210 has at least three outputs. In the Figure three outputs 226,228,230 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 210 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 232 (corresponding to key 106 in Figures 3) shown in the Figure may be plugged into or remove from the microcontroller 210. Alternatively, a bank of DIL switches may be provided to alter the hardware address. The key may have an eight or nine, or ten (or any other number of bits) bit identity which represents the address of the microcontroller 210.

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. 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.

A set of commands exists some of which are global commands which will apply to all of the remote stations in communication with the base station 2, and some of which are individual commands which are issued specific to remote stations in communication with the base station 2.

An alternative to providing the key 106 to provide the identity for the local processing means 98 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 98. 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. To 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 base station that controls the local processing means and receives signals from them.

Other features of the system include a database that maintains the settings for each piece of electrical apparatus controlled by the system. A database entry exists for each piece of apparatus specifying the current settings. It is possible for a user to access the database and modify the particular settings for a particular piece of apparatus. These changes are then acted upon by the system without any further interaction by the user. The particular piece of apparatus that has had its settings changed is updated the next time that particular piece of apparatus is polled.

For instance, a user may notice that the light level occurring from lights controlled by the system is too low for a particular lighting level. He/She can then access the database and cause further lights to be activated; by specifying that light that is not on should be on for that particular setting. The next time that the light that has had its database setting modified is polled that light will be turned on, thus increasing the actual lighting level.

This does not simply apply to lights and may apply to fans, traffic control or information signs, pumps, etc.

Another feature is the control and testing of emergency lighting in areas controlled by the system. As will be appreciated, emergency lighting must emit light for a specified period when mains power fails. The system can monitor this and perform periodic checks.

Each emergency light is provided with a light output monitor much in the same way as the other lights connected to the system. The system is further capable of cutting the power to the emergency light and thus causing that particular light to come on. Therefore, periodically the system may cut power to each emergency light and ensure it still functions to its specification.

In one particular embodiment, the system cuts power to each emergency light once a year and discharges that light for half of its specified life. Therefore, if the light is specified for three hours emission, the system would test it for one-and-a-half hours. During this test the system would monitor the light and ensure it was emitting sufficient light. Further, the system may also test annually (perhaps six months from the half-discharge test) a full discharge of the emergency light whereunto the emergency light is discharged for its fully specified period (and the system monitors it to ensure that it is still emitting light) . Conveniently, the system does not check each light at the same time, but staggers the tests to ensure that the majority of the emergency lighting is still functioning.

It may also be possible to count vehicles using the system and thus control the environment accordingly. This environment may, of course, be a tunnel environment.

The system may provide a complete environmental control. This control is especially applicable to tunnels but may be applicable to other areas with restricted space.

Claims

1. 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.

2. A system according to claim 1 capable of monitoring and controlling a number of pieces of electrical apparatus within a tunnel.

3. A system according to claims 1 or 2 wherein for each housing unit there is run a live, neutral, earth and bus wires.

4. A system according to any one of the preceding claims wherein the remote station (or base station) is adapted to compensate for the failure of electrical apparatus within a particular housing, by utilising other apparatus.

5. A system according to any one of the preceding claims wherein the base station is adapted to poll the remote stations.

6. A system according to claim 5 wherein the base station is adapted to substantially continually poll the remote stations in a pre-set sequence.

7. A system according to claim 6 wherein a control station is provided which is adapted to send commands from a location remote from the base station and remote station to interrupt the pre-set sequence of polling of the remote stations to cause the base station to issue commands affecting electrical apparatus connected to the system.

8. A system according to claim 7 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.

9. A system according to any one of the preceding claims wherein the system is adapted to illuminate an area according to a number of pre-set lighting levels.

10. A system according to claim 9 as it depends directly or indirectly from claim 7 which is adapted to allow the light sources to be stepped through the pre-set levels of illumination by inputting of commands to the control station.

11. A system according to any one of the preceding claims wherein the monitoring means is adapted, in use, to monitor the light intensity output from a light source.

12. A system according to claim 11 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.

13. A system according to claim 11 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.

14. A system according to any preceding claim 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.

15. A system according to any preceding claim wherein the remote station has a selecting means to select how many pieces of apparatus that remote station is monitoring/controlling.

16. A system according to any preceding claim wherein the remote stations are fitted with bus termination means.

17. A system according to claim 16 wherein the bus termination means can be moved to an operational state to terminate the bus.

18. A system according to claim 16 or claim 17 wherein the bus termination means are resistors.

19. A system according to any preceding claim wherein a single remote station is adapted to control and/or monitor a plurality of pieces of electrical apparatus.

20. A system according to any one of the preceding claims wherein a housing unit is provided which contains as least a single piece of electrical apparatus and the remote station.

21. A system according to claim 20 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.

22. A system according to any preceding claim wherein the electrical apparatus comprises a light source, adapted in use to provide light.

23. A system according to any preceding claim that is adapted to control the electrical apparatus within a tunnel.

24. A system according to claim 23 that is adapted to control the electrical apparatus within a road tunnel.

25. 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.

26. A method according to claim 25 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.

27. A method according to claims 25 or 26 comprising wiring a luminaire containing a plurality of electrical apparatus with only a live, neutral, earth and bus wires.

28. A method according to any one of claims 25 to 27 comprising providing an interrupting means allowing a pre-set sequence of remote station polling to be interrupted, and allow specified electrical apparatus to be monitored/controlled by the base station.

29. A method according to any one of claims 25 to 28 comprising controlling a number of pieces of electrical apparatus from a single remote station.

30. A method according to any one of claims 25 to 29 comprising controlling electrical apparatus automatically in a manner dependent upon external parameters.

31. A method according to claim 30 wherein the electrical apparatus is controlled according to external lighting conditions, traffic flow, or time of day.

32. A method according to any one of claims 25 to 31 comprising measuring the light output by a light source.

33. A method according to claim 32 comprising using a light guide to guide light from the light source to a detector.

34. A method according to any one of claims 25 to 33 comprising suing a database provided on the base station to maintain settings for the electrical apparatus.

35. A method according to claim 34 comprising automatically updating the settings of the electrical apparatus when the database is altered.

36. A method according to any one of claims 25 to 35 including testing emergency apparatus connected to the base station via the communication medium.

37. A method according to any one of claims 25 to 36 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.

38. A method according to any one of claims 25 to 37 wherein tunnel lights are monitored/controlled.

39. 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.

40. A method of providing a street with lighting comprising fitting the system of any one of claims 1 to 24 to existing mounting means adapted to support luminaires.

41. 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 1 to 24.

42. 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.

43. 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.