FR2658010A1 - Emergency lighting system for installations powered by electric mains - Google Patents

Abstract

The invention relates to safety lighting systems for buildings. The emergency lighting systems make it possible to light lamps by accumulators in the event of a failure in the electrical distribution network which normally powers the lighting of the building. Emergency units (accumulators and safety lamp) are arranged more or less everywhere and have to be tested regularly. In order to enhance the reliability of these systems, while allowing an easier test, it is proposed according to the invention to transmit, on the electrical network (10) itself, from a central unit (PC) and intended for distant emergency units (Bij), control signals which will trigger the testing of the accumulators of these units. An identification signal of a unit or group of units to be tested is first of all transmitted and recognised by the unit or the group in question; then a test trigger signal operates on this unit, and finally an end-of-test signal is sent; the results of the test can also be transmitted by the network to the central unit.

Description

EMERGENCY LIGHTING SYSTEM FOR
INSTALLATIONS POWERED BY AN ELECTRICAL NETWORK
The invention relates to lighting installations supplied by an electrical distribution network such as for example the low voltage network at 220 volts in
France. The installations concerned can be, for example, the interior or exterior lighting of common parts of buildings (corridors, stairs, elevators, etc.), or even public lighting.

 In installations of this type, safety requires that lighting remains even in the event of a breakdown in the distribution network. Indeed, if the electrical network is cut, all the premises are plunged into darkness, which is unacceptable. In the event of a fire, for example, it is recommended to cut the electrical distribution and we see the catastrophic consequences that this can have if there is no lighting. For this reason, the legislation often provides for an obligation of autonomous emergency lighting installations, that is to say independent of the network.

 Emergency lighting therefore works with accumulators (lead or cadmium-nickel batteries for example). The accumulators are supplied by chargers connected to the electrical network to permanently maintain a sufficient charge. In each place where emergency lighting must be provided, there is an emergency lighting unit which includes such an accumulator with its charger and an emergency lighting lamp. The charger is permanently connected between the network and the accumulator. In the event of a network failure, a detector in the block controls the connection of the emergency lamp to the accumulator.

 However, these emergency installations only make sense if one can be reasonably sure of their operation. In particular it is necessary that the accumulators are not defective and that they are permanently charged.

 They must therefore be tested regularly. The most important classic test is a battery autonomy test. I1 consists in disconnecting the block from the network (simulation of a network failure), connecting the emergency lamp to the accumulator, and leaving this lamp for half an hour or an hour. If at the end of this period it still lights up, the accumulators are considered to be in good working condition and the system is put back into standby state (charging of the accumulators).

 This type of test is relatively tedious since you have to move from local to local to trigger the test and then go back half an hour or an hour later in the same places to identify any blocks that may be defective and to put the blocks back into standby state. . In buildings with a large number of premises, the work involved is considerable: for example, the Grande Arche de la Défense in Paris contains several thousand emergency lighting blocks distributed throughout the construction. Even in smaller premises, for example example of restaurants or other places where the legislation obliges to provide emergency units and to test them regularly, the work may not be considerable, but it is tedious and we realize that because of this managers do not meet safety standards. I1 therefore results in a lack of reliability of the emergency lighting systems.

 An object of the invention is therefore to provide a security lighting system whose reliability is greater.

 For this, the invention provides an emergency lighting system for installations powered by an electrical power network, this system comprising emergency lighting blocks distributed in rooms to be lit, each block comprising an energy accumulator. and an emergency lamp, a charger supplied by the network to maintain the battery in a permanent state of charge, a detector of failure of the supply network, and means for supplying the emergency lamp by the accumulator in the event of detection network failure, characterized in that, in order to allow an improvement in the reliability of the system, the system comprises a central station connected to the supply network, and means for transmitting in the network, from the central station, control signals superimposed on the electrical supply currents normally circulating in the network, and in that each emergency unit includes a means for detecting the control signals transmitted by the network, and means controlled by the detection means for disconnecting the battery from the charging means and for connecting the emergency lamp to the battery for a determined test duration.

 Consequently, the invention starts from the remark that the lack of reliability of the backup systems seems to arise more from the difficulties of organization of the test than from the actual defects of the installation and proposes a system which facilitates this organization by using the network. electrical installation.

 From the central station, a signal will be sent to the emergency units controlling the triggering of the test.

Then there is only to note the results of the test; Several ways are possible to note these results: one can carry out a visual inspection of the emergency lights during the test; it is also possible to store in the backup block information on a fault in the backup power supply and to inspect the stored results after the end of the test; one can finally also provide that the emergency unit includes means for transmitting information over a detected fault via the network.

 To make the operation of the test easier, provision is preferably made for the test control signals sent over the network by the central station to contain specific coding corresponding to a determined backup block (or a determined group of blocks) in order to that only the block or blocks corresponding to the specific code sent react to the test command signals.

 It is also preferably provided that the central station sends a test trigger signal and a signal. end of test.

 Preferably, given the large distances between the central station and the emergency units, it is expected that the control signals are low frequency signals. These signals can then be transmitted through transformers which are present anyway to supply the chargers of the accumulators.

 The preferred solution according to the invention is a transmission of digital signals in the form of pulse trains representing zero or 1 bits, each bit 1 corresponding to the temporary emission on the network of a signal at constant frequency, the absence of this frequency representing a zero bit. However, other systems for modulating the currents of the network are possible for transmitting control signals from the central station to the emergency units; for example, one can imagine that bits 0 are represented by the presence in the network of a first frequency F0 and bits 1 by the presence of a second frequency F1.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows and which is given with reference to the accompanying drawings in which
- Figure 1 shows a general diagram of the installation according to the invention;
- Figure 2 shows a diagram of the central station of the system;
- Figure 3 shows a diagram of an emergency unit according to the invention.

 The emergency lighting system includes a central PC station from which the test sequences can be triggered. This substation is connected to the electrical energy distribution network which is used to supply the normal lighting of the premises. It can transmit test command signals over network conductors. The network conductors are designated by 10 in FIG. 1. By way of example, the network is a 220 volt 50 Hertz alternative network.

 In each room where emergency lighting must be provided, there is an emergency lighting block, designated by Bij, where i represents a block group index among several groups and j represents a block index among several blocks a group. In practice, one can imagine for example that each floor of a building corresponds to a group of blocks if several emergency blocks are provided on each floor.

 The blocks are shown diagrammatically in the figure with a regular distribution, but of course the practical geographical distribution depends essentially on the configuration of the premises to be lit.

 Each block is connected to the network to receive on the one hand energy and on the other hand control signals from the central PC station. Energy is used to charge or keep charged the accumulators contained in the blocks. The control signals are used to initiate and control test operations. In a preferred embodiment, the backup blocks can also transmit test results over the network to the central station.

 The general constitution of the central station is shown in FIG. 2. It preferably comprises a microprocessor circuit for establishing the control signals and for receiving test results in the cases where it is desired to receive them by the network.

 The microprocessor MP is preferably controlled from a personal microcomputer MC, so that a user can program the operation of the microprocessor at will to establish the desired test sequences.

The central station includes an OSC oscillator to establish a frequency F0 which will be used to modulate the currents of the network in order to be able to transmit information to the emergency units distant from the central station. The modulation frequency is preferably a few hundred hertz, for example around 200 hertz, far enough from the frequency used to transport energy on the network (50 hertz) and low enough to be able to be transmitted over long distances without too much losses. The output of the oscillator is applied, through a modulator
MOD, to an AMP amplifier, and the output of the AMP amplifier is applied to the primary of a transformer TR1 whose secondary is connected in series in the electrical distribution network.

 The modulator is simply a switch controlled by the microprocessor to allow either the absence of modulation (no frequency F0 transmitted on the network) or the modulation (frequency F0 transmitted by the transformer on the network). Consequently, as a function of binary data supplied by the microprocessor, trains of pulses will be transmitted over the network, each pulse being constituted by the passage of a frequency F0 during the duration of this pulse. Each pulse corresponds to a bit 1 supplied by the microprocessor and is interpreted on arrival on an emergency lighting block as a bit 1 sent by the central station.

 Other modulation systems can of course be used. The one indicated above has the advantage of simplicity and reliability.

 In the embodiments where the test results arrive by the sector (preferably in the form of a modulation similar to that which is emitted by the central station), provision is made for a filtering cell FLT to be connected to the primary of the transformer; this cell makes it possible to detect the presence of a modulation superimposed on the frequency of the network. The output of this cell is connected to the microprocessor via a demodulation and shaping circuit 12. This circuit 12 transforms the pulse trains received by the FLT filter into a succession of bits 1 and O, to make them usable by the microprocessor. The microprocessor receives the bits and produces information directly usable by the microcomputer MC, this information representing in particular the faults detected in the emergency lighting units.

 FIG. 3 represents a block diagram of the general constitution of an emergency lighting block in the system according to the invention.

 Each emergency lighting unit includes an ACC accumulator, an LS emergency lamp, a circuit for connecting the emergency lamp to the accumulator in the event of a mains power failure, and a circuit for permanently charging the accumulator. through the network.

 To this end, a transformer TR is provided, the primary of which is connected to the energy distribution network 10 and of which a secondary winding TRS1 supplies a circuit CH for charging the accumulator ACC.

 In normal times, the charging circuit is connected to the accumulator to keep the latter permanently charged. But in the event of a mains failure, the accumulator is disconnected from the charging circuit and connected to the LS emergency lamp. This is why a switch K is interposed between the charging circuit or the lamp on the one hand and the accumulator on the other hand.

Furthermore, it will be noted that a battery charging current detector (reference 30) can be interposed between the charging circuit and the battery to provide a fault signal when the charging current of the battery is not within acceptable limits.

 A network voltage absence detector 32 makes it possible to control the switching of the switch K towards the lamp LS when an absence of voltage is detected on the network. This detector 32 is connected to the secondary of the transformer TR upstream of the charging circuit CH. It could however be connected to another winding of the transformer.

 The switch K can however be controlled not only in the event of a network failure, thanks to this detector 32 which detects breakdowns, but also during a voluntary test period, and in particular of autonomy test.

 The autonomy test mainly consists in connecting the accumulator to the LS lamp for a determined period and to examine whether the accumulator still supplies current to the lamp after this period.

 The test is triggered remotely by the central station. The test control signals, transmitted in pulse modulation in the form of the presence or absence of a carrier frequency F0 (for example at 200 hertz), arrive on the network and therefore on the primary of the transformer TR of an emergency unit. . They then pass on a secondary winding TRS2 specially dedicated to the reception of test control signals; one could however also provide that the test control signals are detected on the first secondary winding TRS1.

 A bandpass filter 34 tuned to a narrow band around the frequency F0, is connected at the output of the secondary winding TRS2. This filter makes it possible to separate the signals at frequency F0 from the others and in particular energy at the frequency of the distribution network.

 The filter 34 is followed by a demodulator 36 making it possible to transform the signal at frequency F0 into a pulse whose duration is equal to the duration of presence of the frequency F0.

 In a preferred embodiment of the invention, the signal sent by the central station to a specific emergency lighting unit, for the purpose of testing this unit, comprises a first part intended for the identification of the emergency unit which must be tested and a second part to trigger the block test.

Optionally, it also includes a third part, later, to stop the test.

 Thus, only the emergency unit having received a signal corresponding to its own identification will react to the test trigger signal which will follow the sending of the identification signal, as well as to an end of test signal.

A circuit 38 for detecting the test signals is therefore provided at the output of the demodulation circuit 36. This circuit acts to
1. / receive the identification signal from the central station; compare it to an identification signal prerecorded in the block; authorize the reception of a test trigger signal if the comparison is positive, prohibit it otherwise;
2. / receive a test trigger signal and transmit it to a sequencer 40 which controls the execution of the test;
3. / preferably receive a test end signal at the end of a test to reset the entire circuit awaiting a future test.

 The sequencer 40 controls the switching of the switch K for connecting the accumulator ACC to the emergency lamp LS during the test.

 It also controls a block 42 for storing faults, in which the faults found are stored during the test.

 The main defect that we seek to memorize in block 42 is the absence of sufficient voltage at the terminals of the emergency lamp after a connection duration of half an hour or one hour for example.

A corresponding detector 43, connected to the lamp while the latter is supplied by the accumulator, makes it possible to detect a fault and store it in block 42.

 However, the memory block can be used to memorize other faults such as the insufficiency of the charging current of the accumulator (outside the test periods), thanks to the signal supplied by the charging current detector 30; or a fault in replacement lamps LR, LR 'which are provided to replace the LS lamp if necessary. For example, the lamps LR, LR ′ are connected to a fault detector 44 which detects whether the filament is in open circuit or in short circuit and which provides a corresponding indication to the storage block 42.

 After the execution of the test by the sequencer, an end of test signal can be sent by the central station. Received by the detection circuit 38, it returns the switch K to the charging position of the accumulator. However, provision can also be made for the test to end automatically, the sequencer 40 then comprising means for switching the switch K after a predetermined duration. The transmission of an end-of-test signal by the central station is however preferable since it avoids providing time-delay means in each block.

 For the evaluation of the results of the test, the simplest solution will be a visual inspection of the defects of a block. In this case, provision is made for the memory block 42 to be connected to a fault display block 46. This display block comprises for example a battery of light bulbs: each lamp corresponds to a possible fault and the lighting of the lamp corresponds to the presence of a fault detected and stored in block 42. It is then expected that after the test a person will pass into the premises and visually inspect the display blocks to identify the faults recorded during the test.

 Another solution is the remote transmission of the test results to the central station. This solution is obviously more complex but it can be done in the same way as one transmits control signals from the substation to the emergency units: the information is transmitted in the form of pulses at frequency F0 or preferably at a frequency F '0 different from F0 to avoid interference with signals from the central station. The emergency lighting unit then comprises a transmission circuit 48 receiving information from the fault memorization unit and transmitting corresponding information on a winding TRS3 of the transformer TR, intended for the central station. This transmission is triggered at the end of the test, by the sequencer 40 (when it receives an end of test signal from the central station. The transmission circuit 48 is constituted in a manner analogous to that which is present in the central station, with an oscillator, a modulator and an amplifier. The transmitted signals represent in binary form information stored in block 42.

 In certain cases, the emergency lighting units will be associated in groups, for example a group corresponding to a given floor of a building, this floor comprising several emergency lighting units. In this case, provision can be made for the central station to transmit a code designating a determined group to be tested. The code is recognized by all the blocks in the group and tests are triggered for all these blocks. If the test results are transmitted by the network to the central station, means are provided so that the test results are not transmitted simultaneously for all the blocks of the group. For example, it is expected that the blocks are numbered from 1 to N in a group and that the different results are transmitted with a different time offset (relative to the end of test signal from the central station) from one block to the next. The offset is produced inside each block by a variable time delay from one block to another. Thus, the test results can arrive sequentially and be differentiated from each other although the transmission order is given simultaneously for all the blocks of a group.

Claims (5)

 1. Emergency lighting system for installations powered by a power supply network (10), this system comprising emergency lighting blocks (Bij) distributed in rooms to be lit, each block comprising an energy accumulator (ACC) and an emergency lamp (LS), a charging circuit (CH) supplied by the network to maintain the battery in a permanent state of charge, a detector (32) of failure of the supply network, means ( K) to supply the emergency lamp with the accumulator in the event of a network failure detection, characterized in that, in order to allow improved reliability of the emergency lighting, the system comprises a central station (PC) connected to the supply network (10), a means for transmitting in the network, from the central station, control signals superimposed on the electric supply currents normally circulating in the network, and in that each backup unit comprises u n means (TRS1, 34, 36, 38) for detecting the control signals transmitted by the network, and means (K) controlled by this detection means for disconnecting the accumulator from the charging circuit and for connecting the emergency lamp to the accumulator for a predetermined test time.  2. System according to claim 1, characterized in that it comprises means (43) for detecting a fault in the battery and for storing in the emergency unit information relating to this fault,  3. System according to claim 2, characterized in that there is provided a means (48) for transmitting from the emergency unit to the central station, through the power supply network, the stored fault information.  4. System according to one of the preceding claims, characterized in that it comprises means for transmitting from the central station to an emergency unit, through the supply network, an end of test signal.  5. System according to one of the preceding claims, characterized in that the central station comprises means for transmitting specific control signals for each standby block or block of standby groups to be tested, and in that the standby blocks comprise means for detecting these specific signals and for reacting only to the control signals which concern them.