EP0766905B1 - Remote monitoring and controlling device for a discharge lamp - Google Patents

Description

The present invention relates to a device for control and monitoring remotely from a plurality of discharge lamps.

It applies in particular, but not exclusively, to public lighting, which consists of a large number of candelabras each equipped with a lamp dump. Such candelabras are generally supplied via electrical distribution cabinets located at relatively short distances.

However, discharge lamps have a certain lifespan. So you have to replace regularly, which poses some problems in the case of public lighting. When it comes to monitoring the operation of a large number of candelabras distributed for example, in a city, it is necessary to have a lighting maintenance team that regularly runs a campaign test consisting of lighting the candelabras during the day so that you can be sure visually of the correct functioning of the lamps, and possibly to replace faulty lamps. To ensure good lighting quality with low rate of broken lamps, these campaigns must be carried out frequently.

Practically, the maintenance team moves to change a number reduced lamps, leading to a high maintenance cost.

In addition, it was found that the lighting needs according to the seasons and of the night were not constant. So, for example, during certain hours of the night, it is not necessary to have a light intensity as high as at other times. Substantial savings could therefore be carried out if one could control the intensity of public lighting. he It goes without saying that such an operation can only be envisaged if it can be carried out distance.

To overcome these drawbacks, apparatuses equipped with a telephone transmitter were used which were placed in the electrical distribution cabinets. These devices are designed to detect variations in consumption at the level of the power supply lines of the candelabra, such a variation revealing a lighting fault, and to automatically transmit a fault signal on a telephone line.
It turns out that this device has many drawbacks. First of all, it requires a telephone link with a monitoring station, which presents a significant installation, subscription and telecommunications cost. In addition, it does not make it possible to precisely determine the defective candelabrum, since an electric line supplies several candelabras at the same time.

In addition, to achieve energy savings, we installed dimmers in electrical cabinets on each line to vary simultaneously the intensity of the lighting of all the candelabras connected to the line. However, this solution does not allow the light intensity of each lamp to be adjusted separately.

In an attempt to eliminate the installation and use of communication channels specific, we thought of using carrier currents as a means of transmission. However, it turns out that the scope of this means of transmission is limited to a few hundred meters. It is therefore not applicable to the remote control and telemonitoring of candelabras that may be found distant several kilometers from a central station.

In documents NL-A-8902811 and EP-A-0 062 870, it has been proposed to combine the use of telephone lines and transmission by carrier current, the telephone lines being used to establish a communication link between the central station and local stations to which are connected by current carrying the modules which communicate with the central station. This solution does does not eliminate the use of telephone lines, which has the disadvantages stated above. Furthermore, document EP-A-0 062 870 proposes to insert repeaters on the power lines used for transmission information to ensure transmissions over longer distances. However, the use of repeaters leads to considerably increasing the cost of such an installation.

• des moyens d'émission et de réception pour émettre et recevoir des messages véhiculés par l'intermédiaire de la ligne électrique d'alimentation de la lampe, par courant porteur bidirectionnel modulé, lui permettant de communiquer avec le poste central,
• des moyens pour commander l'allumage et l'extinction de la lampe, en fonction de consignes émises par le poste central, et reçues par les moyens d'émission et de réception, et
• des moyens pour détecter les défaillances de la lampe et en avertir le poste central par les moyens d'émission et de réception.

The present invention aims to eliminate these drawbacks. To this end, it provides a device for the remote control and monitoring of a plurality of discharge lamps supplied by an electrical distribution network, said device comprising a central station and a plurality of control and monitoring modules. a lamp, one module per lamp, installed close to it, each module comprising:

• transmission and reception means for transmitting and receiving messages conveyed by the electric power supply line of the lamp, by modulated bidirectional carrier current, enabling it to communicate with the central station,
• means for controlling the switching on and off of the lamp, as a function of instructions sent by the central station, and received by the sending and receiving means, and
• means for detecting the failures of the lamp and for notifying the central station thereof by the transmission and reception means.

According to the invention, this device is characterized in that the central station comprises an interface circuit connected to the electrical distribution network and which ensures exchange of information between the central station and the distribution network electric, and in that the transmission and reception means of each module are designed to receive all messages conveyed by the power line, and re-issue at least some of the messages which are not intended for them.

Thanks to these provisions, each candelabrum is controlled and monitored independently of the others, in real time and directly from the central station, without the need to provide a telephone link between each electrical distribution cabinet and central station. In addition, each module of control and monitoring can therefore play the role of repeater. Like each candelabrum is generally nearby (a few tens of meters) another candelabrum, this ensures the transmission of messages from the transmitter to the recipient thereof, regardless of the distance between them, and despite the short range of carrier current transmission.

Advantageously, each control and monitoring module includes means for controlling the light intensity of the lamp as a function of instructions issued by the central station.

According to a feature of the invention, each control and monitoring includes means for detecting the deterioration of the state of lamp operation.

According to another feature of the invention, each control and monitoring includes means for counting the operating time of the lamp.

Thanks to these features, it is possible to determine precisely when the lamp must be replaced before it actually breaks down.

La figure 1 représente schématiquement l'architecture d'un réseau de distribution d'électricité utilisant le dispositif de commande et de surveillance selon l'invention ;

La figure 2 montre le schéma de connexion du dispositif de commande et de surveillance avec une lampe à décharge ;

La figure 3 montre en détail le schéma électrique du dispositif de commande et de surveillance ;

La figure 4 montre un ensemble de chronogrammes illustrant le fonctionnement du dispositif de commande et de surveillance ;

La figure 5 montre un circuit d'émission et de réception de messages numériques sur le réseau de distribution électrique.

An embodiment of the device according to the invention will be described below, by way of nonlimiting example, with reference to the appended drawings in which:

FIG. 1 schematically represents the architecture of an electricity distribution network using the control and monitoring device according to the invention;

Figure 2 shows the connection diagram of the control and monitoring device with a discharge lamp;

Figure 3 shows in detail the electrical diagram of the control and monitoring device;

Figure 4 shows a set of timing diagrams illustrating the operation of the control and monitoring device;

FIG. 5 shows a circuit for transmitting and receiving digital messages on the electrical distribution network.

Figure 1 shows a substation 1 for transform the electricity into high voltage that it receives, three-phase low voltage (220 V), to supply a set 2.6 electrical distribution cabinets, including distribution cabinets 6 assigned to public lighting.

Each distribution cabinet 6 for lighting receives in input the three-phase low voltage electric current, and supplies a set of low power lines 7 single-phase voltage. Each of these lines 7 comprises two 15.16 wires for powering a plurality of lamps discharge 11 each associated with a control device and monitoring 10 according to the invention.

The device 10 is designed to transmit and receive information by carrier current, in phase modulation, for example at a frequency of 132 kHz, via the network of electrical distribution, to communicate with a substation central 3 connected to another distribution cabinet 2. For this purpose, the central station is equipped with a computer 5, connected to the electrical network via an interface module 4 which ensures the exchange information between the computer 5 and the network electric.

In FIG. 2, the control and monitoring device 10 is connected to the two wires, phase 15 and neutral 16 of an electric line, the neutral being also connected to one of the terminals of the discharge lamp 11.
To operate such a lamp, a starting circuit 13 connected in parallel with the lamp 11 is used in a known manner, and a ballast 14 with high self-impedance applying a supply voltage supplied by the device 10 to the lamp 11 and to the ignition circuit 13, the ballast 14 having the purpose of limiting the current passing through the lamp 11 when the latter is on.

When the lamp 11 is off, no current flows there crosses. The voltage applied to the input of ballast 14 is then transferred to the priming circuit 13 which allows to apply to the terminals of the lamp 11 a pulse of voltage (of the order of 2000 V) above the ignition threshold of the lamp, causing the lamp 11 to light up, and therefore the passage of current in the latter. Once that the lamp 11 is on, the lamp then being supplied than via ballast 14.

As the impedance of ballast 14 is strongly self-inductive, it it is imperative to have a capacitor 12 in parallel correcting the phi cosine.

In practice, a starting pulse generator is associated with the lamp 11 and ballast 14 assembly.

• un premier étage assurant l'alimentation du dispositif, son couplage au réseau de distribution d'électricité, et la génération d'un signal de synchronisation à partir de la tension Us fournie par le réseau électrique,
• un second étage assurant la commande et la surveillance de la lampe à décharge 11, et
• un troisième étage organisé autour d'un microprocesseur 23 assurant le pilotage de l'ensemble du dispositif.

In FIG. 3, the control and monitoring device 10 comprises three stages, namely:

• a first stage ensuring the supply of the device, its coupling to the electricity distribution network, and the generation of a synchronization signal from the voltage Us supplied by the electric network,
• a second stage ensuring the control and monitoring of the discharge lamp 11, and
• a third stage organized around a microprocessor 23 ensuring the control of the entire device.

• un circuit d'alimentation 21 qui, à partir de la tension Us entre la phase 15 et le neutre 16, fournit les tensions d'alimentation nécessaires aux différents organes du dispositif 10,
• un circuit de couplage 22 connecté entre la phase 15 et le neutre 16, conçu pour assurer l'échange d'informations entre le microprocesseur 23 et le réseau électrique, et
• un circuit de synchronisation 22 également connecté entre la phase 15 et ne neutre 16, conçu pour engendrer un signal logique SS synchrone de la tension électrique Us fournie par le réseau électrique, ce signal logique SS étant appliqué sur une entrée du microprocesseur 23.

The first floor includes:

• a supply circuit 21 which, from the voltage Us between the phase 15 and the neutral 16, supplies the supply voltages necessary for the various organs of the device 10,
• a coupling circuit 22 connected between phase 15 and neutral 16, designed to exchange information between the microprocessor 23 and the electrical network, and
• a synchronization circuit 22 also connected between phase 15 and neutral 16, designed to generate a logic signal SS synchronous with the electrical voltage Us supplied by the electrical network, this logic signal SS being applied to an input of the microprocessor 23.

The coupling circuit 22 can be produced using a transformer or resonant LC type circuit on the frequency of the transmission carrier of carrier current messages.

The second stage, or output stage comprises, in series between phase 15 and ballast 14, an inductor Z1, followed by two switches K1, K2 in series.
The first switch K1, of the relay or triac type, is controlled by the microprocessor 23, from the synchronization signal SS supplied by the synchronization circuit 27, and is intended to apply the voltage Us supplied by the network to the discharge lamp 11, and in particular to the correction capacitor 12 connected to the junction point between the two switches K1, K2. The load then being capacitive, the command of K1 is applied to the zero crossing of the voltage Us of the network.

The second switch K2, of the thyristor or triac type, is intended to power the lamp there via the ballast 14. It is controlled by a logic signal CK2 from a comparator 30. It is also connected to neutral 16 via a capacitive impedance Z3 intended to establish a current Iz when the lamp 11 is absent or broken down.

In parallel with the second switch K2, there is a second synchronization circuit Z2, called lamp synchronization, which provides a logic signal from lamp synchronization SL to 0 when switch K2 is open, and to 1 when the latter is closed.

Mains synchronization circuits 27 and lamp Z2 can be made using photo-couplers so to ensure good electrical insulation between the second and third floors.

• une mémoire EEPROM 24 permettant de sauvegarder des informations, notamment les informations liées à la configuration du dispositif 10,
• un circuit d'émission / réception 25 conçu pour moduler les informations à émettre, fournies par le microprocesseur 23, et envoyer le signal ainsi obtenu au circuit de couplage 22, et pour démoduler et amplifier les signaux d'information transmis par le circuit de couplage 22, et délivrer les informations ainsi obtenues au microprocesseur 23,
• un convertisseur numérique/analogique 29 permettant de convertir en un signal analogique une consigne d'angle d'ouverture fournie par le microprocesseur 23,
• le comparateur 30 à deux états qui compare la consigne fournie par le convertisseur 29 au signal en dent de scie SI engendré par un intégrateur 28 piloté par le signal de synchronisation SL issu du circuit Z2.

The third stage, or control stage, comprises, around the microprocessor 23:

• an EEPROM memory 24 making it possible to save information, in particular information related to the configuration of the device 10,
• a transmission / reception circuit 25 designed to modulate the information to be transmitted, supplied by the microprocessor 23, and send the signal thus obtained to the coupling circuit 22, and to demodulate and amplify the information signals transmitted by the coupling circuit 22, and deliver the information thus obtained to the microprocessor 23,
• a digital / analog converter 29 making it possible to convert an opening angle setpoint supplied by the microprocessor 23 into an analog signal,
• the comparator 30 with two states which compares the setpoint supplied by the converter 29 to the sawtooth signal SI generated by an integrator 28 controlled by the synchronization signal SL coming from the circuit Z2.

Furthermore, the microprocessor 23 is connected to two LEDs, a red LED 31 for signaling faults, and a green light 32 for signaling the states of operation. It is also connected to a button 33 of on / off, and a button 34 which allows, when changing of lamp 11, triggering transmission an initialization signal to the central station 3, indicating the effective replacement of the lamp 11, and allowing the reset of a usage time counter of the lamp 11.

As previously mentioned, the microprocessor 23 communicates with central station 3 by messages transmitted by carrier current, in phase modulation, for example at a 132 kHz frequency, via the distribution network electric. To this end, each lamp 11 controlled by the central station 3 is identified by an identification code which is inserted in each message exchanged with the post central.

Operation of the control and monitoring device is illustrated by the timing diagrams in Figure 4.

Curve C1 shows that the voltage Us between phase 15 and neutral 16, or the voltage Uc at the junction point between the two switches K1, K2, has a shape sinusoidal. Curve C2 shows the shape of the logic signal sector synchronization SS from circuit 27, which changes logic state whenever the line voltage They cancel each other out.

On a running order from central station 3, the microprocessor 23 controls switch K1 when switching to zero of the mains voltage Us, thanks to the synchronization signal SS sector shown by curve C2. Detection of a voltage UK2 at the terminals of switch K2 by the lamp synchronization circuit Z2 results in release of the integrator 28. When the output of the integrator 28 reaches a setpoint 46, the comparator 30 delivers a control voltage CK2 which allows the ignition of switch K2. Switch K2 is controlled at its turn with a set point at zero, implying an opening angle 41 void. As the charge of K2 is selfic, the current IB crossing it is therefore late by a certain phase shift 42 with respect to the voltage Uc (curve C4).

Before tripping K2, the UK2 voltage across its terminals is very much higher than its trigger point 45, and K2 becomes passing for the current alternation (curve C5).

In fact, the current IB flowing through the switch K2 determines the alternation. K2 therefore remains on as long as the current IB did not reach a value close to zero. The voltage UB (curve C3) across the ballast 14 is then practically identical to the mains voltage Us.

The lamp synchronization circuit Z2 delivers a signal logic SL to 1 whenever absolute value of the UK2 voltage across switch K2 exceeds threshold 45, i.e., during periods when switch K2 is blocked (curve C6). This logic signal SL is sent to microprocessor 23, and is applied as input to the integrator 28 which delivers a sawtooth signal which remains zero when the lamp synchronization signal SL is at logic level 0 (curve C7).

The circuit described above makes it possible to reduce the voltage applied to lamp 11, in order to reduce the intensity of lighting. Indeed, the microprocessor 23 can impose a setpoint in the form of binary data applied to the input of the analog / digital converter 29. If this setpoint data is not zero, we get at the output of comparator 30, a logic signal at 1 when the signal in integrator output exceeds threshold 46 defined by this setpoint, and zero otherwise, the signal CK2 from comparator 30 used to control the switch K2 (curve C8).

We can notice on curve C8 that, thanks to the shape in sawtooth of signal SI, switch K2 receives CK2 control pulses late with respect to the pulses UK2 voltage across its terminals, delaying the tripping of switch K2. The periods during which current IB (curve C4) and voltage UB (curve C3) remain zero, corresponding to the angle 41, are thus lengthened, which causes a decrease in the effective intensity of the current IB and the RMS voltage applied across the lamp 11, and therefore a decrease in the intensity of the lighting produced by lamp 11. We can thus vary opening angle of 0 up to a value close to 45 °, which reduces the effective supply voltage of the lamp 11 from 0 to about 20% of the voltage Us, corresponding a reduction in energy consumption from 0 to 60%.

Furthermore, it is necessary to reduce in a way progressive, the lamp supply voltage at discharge 11 in order to avoid untimely stalls, and so the extinction of it. This is why this reduction is controlled by microprocessor 23 by small successive steps, gradually increasing the value of the setpoint applied at the converter input digital / analog 29. In practice, to improve this progressiveness, a time constant can be added at the output of converter 29.

Curves C9 to C13 illustrate the detection of lamp stalls.
The stall or a breakdown of the lamp results in the absence of current IB at the input of the ballast 14. The load is then solely determined by the impedance Z3 placed between the switch K2 and the neutral 16, this load being insufficient to maintain switch K2 in the on state. The capacitive impedance Z3 is then crossed by a current Iz in phase advance 43, and practically in phase quadrature with the voltage Uc at the input of the switch K2 (curve C9). The resistive impedance of Z2 and the capacitive impedance of Z3 then form a voltage divider bridge so that the resulting voltage UK2 across the terminals of switch K2 is less than the trigger voltage threshold 45 of the latter (curve C10 ).

The detection threshold 44 of the synchronization circuit lamp Z2 being far below the trigger threshold 45 of switch K2, the lamp synchronization signal SL is therefore at logical level 1 in the vicinity of each passage at zero of the mains voltage Us (curve C11).

Curve C12 shows the signal SI at the output of the integrator 28, obtained from the lamp synchronization signal SL showing the shape of curve C11. Curve C13 shows the form of the switch command signal CK2 K2, which is at logic level 1 when curve C12 exceeds setpoint 46. However, as before mentioned, the UK2 voltage across the K2 switch is below the trigger threshold 45 of it it therefore remains blocked regardless of the command given to it applied.

The microprocessor 23 can determine whether the lamp 11 is off or on by comparing synchronization signals SS sector and SL lamp. If at the moments of the fronts amounts and / or descendants of the SS signal correspond to moments when the SL signal is zero (curves 2 and 6), the lamp is detected on. Otherwise (curves 2 and 11) the lamp is detected off.

There is thus thus a simple and effective device for controlling the light intensity of the lamp 11 and determining the proper functioning of the latter.
Indeed, when the lamp 11 is in good working order, the load is self-inductive. The switch K2 therefore has a hundred volts at its terminals to be triggered, and when the mains voltage Us crosses zero, the lamp synchronization signal SL is also at zero.
When the lamp goes off, the load becomes capacitive. The switch K2 therefore no longer has enough holding current IB, and the voltage at its terminals UK2 is insufficient to be able to be triggered. In addition, when the mains voltage Us crosses zero, the lamp synchronization signal SL is at 1.

In addition, the programming instructions for each control and monitoring device 10 are fixed. However, each device 10 has instructions variables that can change depending on the state of the lamp he controls. This state is determined during reduction regime: if microprocessor 23 realizes that during the reduction in lighting intensity, the lamp goes off, then it decreases the reduction rate planned. The microprocessor 23 advantageously has 7 reduction rate, and when it reaches an alert rate predetermined, it warns central station 3 of the degradation of the lamp 11.

The microprocessor 23 is further designed to declare in a lamp 11 which no longer tolerates reduction or which can no longer prime at maximum voltage. In practice a delay of a few minutes is left to the ignition circuit 13 before declaring the lamp 11 in failure and notify the central station 3.

When the lamp 11 is changed, the operator activates the button 34, allowing on the one hand to warn the post central 3 of the lamp change, and on the other hand reset variable parameters such as the rate of reduction of lamp lighting.

• un code d'identification de la lampe,
• les heures d'allumage et d'extinction de la lampe,
• la période et le taux de réduction de l'intensité d'éclairage,
• la durée d'utilisation de la lampe depuis sa mise en service, et
• l'état de la lampe, en bon fonctionnement, dégradé ou en panne.

The computer 5 of the central station 3 is connected to a database 8 where information concerning each lamp is stored and in particular:

• a lamp identification code,
• the lamp on and off times,
• the period and the rate of reduction of the lighting intensity,
• the duration of use of the lamp since it was put into service, and
• the state of the lamp, in good working order, degraded or broken down.

Thus, knowing the hours of ignition and extinction of each lamp 11, the computer 5 of the central station 3 can count the operating time of each lamp, and compare this duration to an alert threshold, the crossing of this threshold indicating that the lamp is to be replaced. The central station 3 can thus draw up a list of lamps with replace by grouping the overrun information this alert threshold, for lamp degradation detection, and lamp failed, in order to prepare and trigger the replacement interventions, when the lamps to be replaced are in sufficient number. We can thus group interventions to reduce the unit cost, the maintenance team being warned of changes in lamps to provide before they are really out of order.

These provisions therefore make it possible to considerably reduce the unit cost of maintenance per candelabrum, and adapt the light intensity of each candelabra, and thus realize significant savings of energy.

In FIG. 5, the transmit / receive circuit 25 shown in FIG. 3 is a phase modulation modulator / demodulator, of the synchronized asynchronous type, comprising for example, a first EXCLUSIVE OR gate 53 which combines a carrier F _t with the signal of the data to be sent from the connection terminal T _x of the microprocessor 23, and delivers a signal modulated in phase or in phase opposition with the carrier as a function of the logic level 0 or 1 of the data to be sent.

The output of gate 53 is connected to coupling circuit 22 which is either positioned in transmission or in reception thanks to a signal T _x R _x transmitted by the microprocessor 23 and applied to the E / R input of coupling circuit 22.
When the coupling circuit 22 is positioned in transmission, it has a low output impedance, of the order of a few Ohms. It also makes it possible to filter the signal emitted to transform it into a sinusoidal signal.

• une porte OU EXCLUSIF 52 dont une entrée est reliée à la sortie de l'oscillateur 54,
• un échantillonneur-bloqueur constitué par un générateur d'impulsions 56 qui commande un interrupteur 60 dont l'entrée est connectée à la sortie de la porte 52, et qui permet de charger un condensateur C_d relié à la masse,
• une porte OU EXCLUSIF 51 dont les entrées sont connectées aux sorties de la porte 52 et de l'interrupteur 60, et
• un filtre-intégrateur 62 présentant une constante de temps RC, relié à la sortie de la porte 51, et fournissant le signal de commande U₀.

The carrier Ft is obtained by means of an oscillator 54 controlled in frequency and in phase by a control loop applying a control voltage U ₀ at the input of the oscillator 54. This control loop comprises:

• an EXCLUSIVE OR gate 52, one input of which is connected to the output of the oscillator 54,
• a sampler-blocker constituted by a pulse generator 56 which controls a switch 60 whose input is connected to the output of door 52, and which makes it possible to charge a capacitor C _d connected to ground,
• an EXCLUSIVE OR gate 51 whose inputs are connected to the outputs of gate 52 and of switch 60, and
• a filter-integrator 62 having a time constant RC, connected to the output of gate 51, and supplying the control signal U ₀ .

The pulse generator 56 delivers a signal d (F _t ) consisting of one pulse at each edge of the input signal F _t , that is to say, two pulses per period of the signal F _t . When the switch 60 is open between two pulses of the signal d (F _t ), the voltage across the capacitor C _d remains blocked at logic level 0 or 1 of the last value of the voltage sampled by the switch 60 when the latter it was closed during a pulse supplied by the generator 56.

Furthermore, the signal T _x R _x also serves to control a switch 57 which makes it possible to select either the data signal F _x received by the coupling circuit 22, or a signal F ₀ generated by an oscillator 58, preferably controlled by a quartz. This signal F ₀ has a periodic rectangular voltage having a constant frequency, equal to that of the carrier.

The signal F ₀ or F _x selected by the switch 57 is sent to the input of the EXCLUSIVE OR gate 52. The control loop thus makes it possible to calibrate the frequency and the phase of the signal F _t delivered by the oscillator 54, on transmission, on those of the signal F ₀ , and on reception, on those of the received signal F _x .

On transmission, the switch 57 is positioned by the signal T _x R _x so as to apply the output signal F ₀ of the oscillator 58 to an input of the gate 52. The signal F ₀ being constant, the signal F _t generated by the oscillator 54 is also constant, as is the signal d (F _t ) generated by the pulse generator 6 and which controls the switch 10.
Thus, the signal passing through the switch 60 charges the capacitor C _d at logic level 0 or 1, which blocks the voltage across the capacitor at logic level 0 or 1 from the last sample taken to the next sample. The filter 62 makes it possible to obtain a voltage U ₀ for controlling the oscillator 54 so that the signal F _t corresponds in frequency to the signal F ₀ .

The signal T _x emitted by the microprocessor 23 begins with a start bit to allow the recipient of this signal to remove the uncertainty on the initial phase of the signal. On reception, the value of this start bit can be used to determine whether or not to reverse the value of the following bits contained in the received signal.

It follows from the truth table of the EXCLUSIVE OR function that during the time intervals when the data signal T _x emitted by the microprocessor 23 is at logic level 0, the voltage at the output of gate 53 corresponds in shape and in phase exactly at the carrier F _t . When the data signal T _x is at logic level 1, the signal F _t + T _x at the output of gate 53 corresponds in shape and in phase to the carrier F _t phase shifted by 180 ° (phase inversion).

On reception, the coupling circuit 22 is positioned on reception by the signal T _x R _x , it then has a high input impedance, of the order of a few hundred Ohms, so as to transmit the data signal F _x from the electrical network to an amplifier 59 which also performs a filtering of the parasitic frequencies circulating on the electrical distribution network. The switch 7 is positioned by the signal T _x R _x so as to apply the signal Fx to the input of the gate 52.

The EXCLUSIVE OR gate 52 then combines the carrier with the received signal F _x , to obtain a signal F _t + F _x at logic level 0 or 1 depending on whether the received signal F _x is in phase or in phase opposition with the carrier F _t , the signal F _t + F _x being introduced into the control loop described above.

The sampler-blocker constituted by the generator 56 which controls the switch 60, as well as the capacitor C _d makes _it possible to reset the received signal F _x at constant phase with respect to the frequency F _t , and supplies the microprocessor 23 with the demodulated signal U _d available across the capacitor C _d . This demodulated signal is applied via an inverter 63, on the one hand to the input R _x of the data received from the microprocessor 23, and on the other hand to the input P for detecting the carrier of the microprocessor 23 , through a pulse generator 64 and a time constant circuit 65. In this way, the microprocessor 23 can determine whether it should wait for reception of a message in the event of detection of the carrier on its R _x input, and if it can send a message in the absence of a carrier.

The use of a blocker sampler therefore makes it possible to carry out very fast demodulation of the received signal. So the digital transmission speed expressed in kilobits per second, theoretically can reach the speed of the carrier.

So, for example, with a carrier frequency equal to 135 kHz, this circuit can send and receive a signal digital at the speed of 90 Kilo-bits per second.

To overcome the reduced range (a few hundred meters) of the carrier current transmission, the microprocessor 23 receives all messages detected by the coupling circuits 22 and reception 25, and control re-transmission of messages which are not intended for it. This solution allows to control and monitor a large number of candelabras, thanks to the demodulation principle which achieves transmission speeds high.

Claims (17)

1. Device for remote controlling and monitoring a plurality of discharge lamps fed by an electric distribution network, said device including a central station (3) and a plurality of modules (10) for controlling and monitoring a lamp at the rate of one module (10) per lamp (11) installed close to the latter, each module including:

   transmission and receiving means (22,23,25) for transmitting and receiving messages carried by the electric feed line (15, 16) of the lamp(11) by a modulated bidirectional carrier current enabling it to communicate with the central station (3),

   means to control the switching on and off of the lamp according to instructions transmitted by the central station (3) and received by the transmission and receiving means (22,23,25), and

   means to detect failures of the lamp (11) and have the central station (3) informed of these by the transmission and receiving means (22,23,25),

      characterised in that the central station (3) includes an interface circuit (4) connected to the electric distribution network and which ensures the exchange of information between the central station and the electric distribution network, and in that the transmission and receiving means (22,23,24) of each module have been designed so as to receive all the messages borne by the electric line (15, 16), and retransmit the messages not intended for them.
2. Device according to claim 1, characterised in that each module (10) includes means to control the light intensity of the lamp (11) according to instructions transmitted by the central station (3).
3. Device according to claim 1 or 2, characterised in that each module (10) includes means to detect a deterioration of the operating state of the lamp (11).
4. Device according to one of the preceding claims, characterised in that each module (10) includes means to detect that the lamp (11) is switched on.
5. Device according to one of the preceding claims, characterised in that each module (10) includes means to count the operating period of the lamp (11).
6. Device according to one of the preceding claims, characterised in that the means (22,23,25) for communicating with the central station (3) transmit and receive messages transmitted by a phase modulated carrier current via the electric distribution network.
7. Device according to one of the preceding claims, characterised in that the means (22,23,25) for communicating with the central station (3) transmit and receive messages transmitted by a modulated phase carrier current at a frequency of 132 kHz via the electric distribution network.
8. Device according to one of the preceding claims, characterised in that the means (22,23,25) for communicating with the central station (3) have been designed so as to receive all the messages borne by the electric line (15,16) and retransmit the messages not intended for them.
9. Device according to one of the preceding claims, characterised in that each module (10) includes a first switch (K1) for triggering turning on and off the lamp (11) and controlled by a microprocessor (23), and a second switch (K2) associated with a control circuit (Z2,28,29,30) for varying the light intensity of the lamp (11) according to instructions transmitted by the microprocessor (23).
10. Device according to claim 9, characterised in that said second switch (K2) remains locked open when the lamp (11) is not working, each module (10) including in parallel with the second switch (K2) a detection circuit (Z2) providing the microprocessor (23) with a signal representing the state of the second switch (K2) including the on/off state of the lamp (11).
11. Device according to claim 9 or 10, characterised in that the defective state of the lamp (11) is detected via the second switch (K2) associated with the control circuit (Z2,28,29,30) progressively reducing the voltage applied to the terminals of the lamp (11), the lamp being declared defective by the microprocessor (23) when the off state of the lamp (11) is detected before having reached a certain lighting intensity reduction rate.
12. Device according to one of the preceding claims, characterised in that the central station (3) includes a computer (5) connected to the electric network by means of an interface circuit (4) for transferring data between the computer (5) and the electric network, and to a data base (8) where the information is stored concerning each lamp (11) controlled and monitored by the central station (3), this information including for each lamp :

    a lamp identification code,

    the lamp on/off times,

    the period and lighting intensity reduction rate,

    the use period of the lamp from the time it was put into service, and

    the state of the lamp, namely whether it is defective, functioning properly or not functioning.
13. Device according to one of the preceding claims, characterised in that the instructions for reducing the light intensity of the lamp (11) is progressively applied by the microprocessor (23) so as to avoid the lamp (11) going out.
14. Device according to one of the preceding claims, characterised in that the computer (5) of the central station (3) includes means for comparing the period of use of each lamp (11) with an alarm threshold and draws up a list of lamps to be replaced including broken down or defective lamps and those lamps whose period of use exceeds the alarm threshold.
15. Device according to one of the preceding claims, characterised in that the transmitting and receiving means (22,23,25) include a synchronised asynchronous phase modulation demodulator/modulator circuit able to transmit numerical data with the aid of a carrier wave (Ft) having the shape of notches, this circuit including a first OR EXCLUSIVE gate (53) to which the carrier wave (Ft) and the signal (Tx) containing the data to be transmitted are applied on input and whose outgoing voltage is in phase or in phase opposition with the carrier wave (Ft) according to the logic level 1 or 0 of the transmitted data element, and a second OR EXCLUSIVE gate (52) to which the carrier wave (Ft) and the received signal (Fx) are applied on input and whose outgoing voltage is at the logic level 0 or 1 according to which the signal received (Fx) is in phase or phase opposition with the carrier wave (Ft)
16. Device according to claim 15, characterised in that the demodulator/modulator circuit further includes :

    an oscillator (54) generating the carrier wave (Ft) and whose phase is controlled by a voltage (UO) so as to be synchronous on frequency and in phase on transmission with a signal of (FO) generated by an oscillator (58), and on reception with the received signal (Fx), and

    a sampler/locker to which the signal derived from the second OR EXCLUSIVE gate (52) is applied and being designed so as to take samples of the signal derived from the in phase controlled oscillator (54) at a frequency double that of the carrier wave (Ft) and to deliver an outgoing voltage which remains locked at the logic level 0 or 1 of the last sample taken so as to demodulate the received numerical data transmission signal (Fx).
17. Device according to claim 16, characterised in that the phase controlled oscillator (54) is controlled in phase by a voltage (UO) provided by an automatic control loop including:

    the second OR EXCLSUIVE gate (52),

    the sampler/locker,

    a third OR EXCLUSIVE gate (51), and

    an integrator filter (62).

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