FR2652666A1 - System for transmitting a signalling signal by the electricity mains and security system using this transmission system - Google Patents

Abstract

The invention relates to a system for transmitting a signalling signal by the electricity mains and a security system which is provided for an installation for forced ventilation and removal of flue gases produced by boilers installed in living quarters and which use this transmission system. The transmission system comprises a transmitter which transmits a signalling signal F1 as long as a given condition is not fulfilled, and which no longer transmits a signal if this condition is fulfilled, receivers which deliver a control signal when they do not receive the signalling signal transmitted by the transmitter, and n repeaters RE1 to REn which receive the signalling signals transmitted by the transmitter or from other repeaters and which deliver a new signalling signal. A repeater REi transmits its signalling signal Fi when it detects the end of the transmission of a signalling signal Fi-1 by another repeater REi-1 or by the transmitter. The receivers are provided to receive all the signalling signals F1 to Fn+1 transmitted by the transmitter and the repeaters and deliver a control signal when they no longer receive signalling signals over a predetermined time T. The invention also relates to a security system for a controlled mechanical ventilation installation which uses this transmission system.

Description

 The invention relates to a system for transmitting a signaling signal by the electrical network and to a security system, in particular a security system provided for an installation of forced ventilation and evacuation of the combustion gases produced by installed boilers. in residential premises, which use this transmission system.

 Such a ventilation installation consists of a set of vertical ducts to which is connected, at each living room of a building, a ventilation outlet on which is mounted the flue gas discharge pipe of a boiler.

All of these vertical ducts are connected to a mechanical fan placed at the top of the building and ensuring the ventilation of the premises and the forced evacuation of gases from the boilers.

 If the fan malfunctions, the combustion gases from the boilers can accumulate in the vertical ducts, thus creating the risk of accident. It is therefore necessary to provide a security system which detects this malfunction and which then stops the boilers of the installation.

 Such systems generally consist of a detector for the proper functioning of the fan, a transmitter which emits a signaling signal if this operation is poor, and receivers which control the stopping of the boilers upon receipt of the signaling signal emitted. by the transmitter.

 For example, the document FR-A-2 623 602 describes a device for transmitting a safety signal for a mechanical ventilation installation of a building comprising a fan having a good functioning detector connected to a transmitter emitting a signal of high frequency carried by a wire to which is connected a receiver, disposed in each housing, the control output of which is connected to the corresponding boiler. The system described is positive security, that is to say placing each boiler in the impossibility of operating in the absence of significant information of the correct operation of the fan.

 The document FR-A-2 624 264, which is an addition to the patent of the previous document, specifies that the transmission line between the transmitter and the receivers is constituted by a portion of the general electrical supply network of the housing of the building.

 The use of the electrical network as a transmission medium has advantages as regards the ease of installation and subsequent modifications of the transmission system which is fitted, for example, to a security system of the type mentioned above. Indeed, it is not necessary to provide a network of special lines to be connected to the heating installation of each dwelling.

 However, for a security system which uses the electrical network as the transmission medium to be reliable, it is necessary that the receivers do not react to the parasites present on the lines and can discriminate the useful signals emitted by the transmitter of these parasites. . To do this, most of the transmission systems by the electric network use a transmitter modulating, preferably, in frequency a carrier of frequency ranging between 100 and 150 kHz. The detection by receivers of frequency modulated signals is less sensitive to interference than that of amplitude modulated signals.

 Other problems related to the use of the electrical network as a transmission medium are to be resolved, in particular problems related to the physical characteristics of the lines constituting the building's distribution network. Indeed, if these lines are long, some receivers, the furthest from the transmitter, receive very weak and, sometimes, undetectable signals, which makes the security system inoperative. In the same vein, the lines of the distribution network can, in certain places of the installation, present impedances such that no high frequency signal can be transmitted. Receivers located downstream of these locations receive no signal from the transmitter.

 It is known to solve these various problems by increasing the power of the transmitter, thus hoping that the receivers receive a signal of a sufficient level to operate it correctly. This solution is however not satisfactory. Indeed, the transmitter should not be too powerful because it could disturb an installation of the same type mounted in a building or a set of neighboring premises.

 The object of the invention is therefore to provide a system for transmitting a signaling signal which uses the power supply network as the transmission medium, which is insensitive to parasites present on this network, which is independent of physical characteristics of the lines constituting this network, and the transmitter of which is not too powerful so as not to disturb a building or a set of neighboring premises equipped with a similar system.

 To this end, the invention relates to a system for transmitting a signaling signal by the electrical network comprising a transmitter injecting into the electrical distribution network signaling signals, consisting of a carrier modulated in frequency by a tone signal. at voice frequency, as long as a given condition is (or is not) fulfilled and no longer injecting any signal when this condition is not (respectively is) fulfilled, receivers delivering a control signal when they do not no longer receive any signaling signal.

 According to a characteristic of the invention, this transmission system comprises a plurality of repeaters receiving the signaling signals transmitted by the transmitter or other repeaters of this plurality and which deliver another signaling signal consisting of a carrier modulated in frequency by a tone signal.

According to a characteristic of the invention, the first repeater waits for the end of the transmission, by the transmitter, of the first signaling signal, constituted by the modulation of a first carrier by a first tone signal and transmits in turn a second signaling signal, consisting of a second carrier, of the same frequency as the first carrier, modulated by a second tone signal different from the first tone signal, then the second repeater waits for the end of the emission of the second signal signaling by the first repeater to transmit in turn, on the network, a third signaling signal, consisting of a third carrier frequency modulated by a third tone signal different from the other tone signals, and so on until a last repeater, waiting for the end of the transmission of an n signal signal
e tion by a penultimate repeater, in turn transmits a (n + l) e signaling signal, consisting of a carrier frequency modulated by a (n + 1) tone signal different from other tone signals, transmissions (n + 1) signaling signals which do not overlap in time. The receivers are designed to receive all the signaling signals transmitted by the transmitter and the repeaters and deliver a control signal only when they have no longer received, for a predetermined time, any signaling signal.

 According to another characteristic of the invention, the signaling signal emitted by the transmitter and those emitted by the repeaters have voltages whose value is of the order of 0.7 volts.

 The invention also relates to a security system comprising a security condition detector and security devices.

 According to one characteristic, this security system comprises a transmission system according to the invention and the detector controls the transmitter so that it transmits a signaling signal when a security condition is met, and that it transmits no signal when this condition is no longer fulfilled, the receivers delivering a control signal to the safety devices when they no longer receive any signaling signal for a predetermined time.

 The invention also relates to a security system for a controlled mechanical ventilation installation consisting of conduits for evacuating combustion gases from boilers in premises of a building, conduits connected to a fan sucking these gases and discharging them to the outside. , comprising a fan functioning detector and contacts controlling the start / stop of each boiler.

 According to one characteristic, this security system comprises a transmission system, such as that described above, the detector controlling the transmitter so that it emits the first signaling signal when the operation of the fan is normal and that it does not emit no signal when this operation is no longer normal, the receivers controlling the contacts to stop the boilers when they no longer receive any signaling signal from the transmitter and / or the repeaters for a predetermined time.

The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of a preferred embodiment of the invention, said description being made in relation to the accompanying drawings, among which:
Fig. 1 schematically represents a mechanical ventilation installation of a building equipped with a transmission system according to the invention, and
Fig. 2 is a time diagram showing the sequencing of the transmissions of the transmitter and the repeaters of a transmission system according to the invention.

 The installation for ventilating the premises of a building and extracting the combustion gases from these premises, as shown in FIG. 1, essentially consists of vertical ducts 1 to which are connected, at each room, symbolically represented here by their floor 2, ventilation outlets 3. These vertical ducts are connected at their upper end to a fan 4. On each of the ventilation openings 3, the exhaust pipe 5 for the burnt gases from a boiler 6 is mounted.

 In normal operation, the boilers 6 reject their combustion gases via the conduits 5, which, sucked in by the fan 4, are extracted from the vertical conduits 1 and discharged outside the building by a chimney 7.

This installation further comprises a signaling signal transmission system which essentially consists of a transmitter 8 placed near the fan 4 and receivers 9 each associated with a boiler 6. The transmitter 8 receives a signal for controlling a detector 10 for correct operation of the fan 4 and delivering a signaling signal on a pair of wires 11. The detector 10 is, for example, made up of a contact 12, forming part of a relay, which is closed when fan operation is normal, and which is open when the fan fails. This contact can, for example, control the power supply to the transmitter 8. When it is closed, the transmitter 4 is supplied with power and emits a signaling signal, whereas when it is open, the transmitter does not is no longer powered and therefore no longer works. The transmitter is of moderate power so as not to disturb other transmission systems mounted on neighboring installations. In practice, the signaling signal emitted by the transmitter 8 has a voltage whose value is of the order of 0.7 effective volts, value measured for one minute using a peak detector on a fictitious network , in accordance with paragraph 8.2.1 of the
th
Publication of CISPR, 2 edition 1987. The receivers 9 receive, on pairs of wires 13, the signaling signals emitted by the transmitter 8 and control the opening or closing of contacts 14 forming part of relays integrated into the receivers. it will be explained later, in normal operation of the installation, these contacts 14 are closed and maintain the boilers 6 in their operating state and, in the event of failure, they are open and control the stopping of the boilers. When the receivers are out of operation, the contacts 14 are also open. This particular mounting of the transmitter and receivers allows for a positive security installation. The pair of wires 11 is connected, by an electrical outlet 15, to the electricity distribution network of the building 16, represented symbolically here by two wires. Likewise, the pairs of wires 13 are connected, by electrical outlets 17, to the building's electricity distribution network 16.

 In Fig. 1, the contact 12 of the detector and the contacts 14 of the boilers being closed, this figure represents the case where the operation of the installation is normal.

 This transmission system further comprises a plurality of repeaters 18 which receive, over a pair of wires 19, the signaling signals transmitted by the transmitter 8 or other repeaters 18 of this plurality, and which deliver, over the same pair of wires 19, new signal signals. For the same reason as above, these signaling signals have substantially the same amplitude as the signaling signal emitted by the transmitter 8, that is to say of the order of 0.7 volts, measured under the same conditions . The manner in which they are arranged, them and the signaling signal emitted by the transmitter, will be described later. The pair of wires 19 is connected to the electrical distribution network 16 by means of a power outlet 20. The repeaters 18 are arranged in locations distributed throughout the building so that the receivers receive at least one signaling signal with a level sufficient. The number of these repeaters 18 is independent of that of the receivers 9.

 The transmitter 8 and the repeaters 18 inject a medium frequency carrier on the distribution network, frequency modulated by low frequency signals. Advantageously, the carrier has a frequency of 144 kHz and the low frequency signals are tone signals with voice frequencies.

 The assembly formed by the transmitter 8, the repeaters 18, and the receivers 9 constitutes a system for transmitting a signaling signal which could be used in a security system comprising a detector of a security condition and devices safety devices, such as devices cutting off the power of devices whose operation may be dangerous if the danger condition is met, or alarm devices, etc. The following description is that of the use of a transmission system according to the invention in a security system for a ventilation installation of premises of a building. It could obviously be used in other systems in which a signaling signal must be transmitted from one location to at least one other remote location.

 The sequencing of the transmission between the transmitter 8, the repeaters 18 and the receivers 9 is shown in FIG. 2. In normal operation, the contact 12 of the detector 10 is closed and the transmitter 8 modulates in frequency a carrier pl with a tone signal ql to form a signaling signal FI which is injected into the electrical network for a period tl d 'about a second.

A repeater 18, called here RE1, waits for the end of the transmission of the signaling signal F1 and, at this time, modulates in frequency a tone signal q2, different from the tone signal ql, on a carrier p2, of the same frequency that pl, to form a signaling signal F2 which is in turn injected into the network for a duration t2, of the order of one second, too. Similarly, at the end of the transmission of the signal F2, the repeater named here RE2 modulates a tone q3 on a carrier p3, with the same frequency as pl, and forms a signaling signal F3 which is injected into the network. 'there are n repeaters, the repeater REn waits for the end of the signal Fn and then emits, for a duration tn of about one second, a signaling signal Fn + 1. As long as the fan operation is normal, the described cycle is repeated. The duration c of a cycle, which corresponds to the duration between two transmissions of a signal F1, is sufficient for the last repeater REn to be able to transmit its signal Fn + 1 without it covering the signal F1 transmitted by the transmitter 8.

 The receivers 9 are designed to receive the signals F1 to Fn transmitted by the transmitter 8 and the repeaters 18. On reception of at least one of these signals with a periodicity corresponding substantially to the duration c of a transmission cycle of the transmitter 8, the receivers 9 keep the contacts 14 closed, which does not modify the operating state of the boilers 6.

 In the event of failure of the fan 4 of the ventilation installation, the contact 12 of the detector 10 opens, the transmitter 8 no longer emits a signaling signal, and the repeaters 18, no longer receiving any signal, do not neither do. This situation arises at time t in FIG. 2. The receivers 9 no longer receive signaling signals and then control the opening of the contacts 14, which controls the stopping of the boilers 6.

In fact, the boilers are stopped when the receivers have no longer received signaling signals for a predetermined duration T greater than the duration c of a cycle of the transmitter 8.

 It will be noted that the security system described is a positive security system. Indeed, any failure of any of the elements that constitute it, for example, the transmitter, repeaters or receivers, controls the shutdown of the boilers.

 In the case of the use of a transmission system according to the invention in a security system comprising a detector of a security condition and security devices, the detector controls the transmitter so that it transmits the signal signaling IF when the safety condition is fulfilled, and so that it does not emit a signal when this condition is no longer fulfilled. The repeaters transmit, in the same way as previously, the signaling signals F2 to Fn + 1 and the receivers deliver a control signal to the safety devices when they have no longer received any signaling signal F1 to Fn + 1 for a time predetermined.

On reception of this command signal, the safety devices stop, for example, the devices to which they are connected, or emit an alarm signal.

Claims (4)

 1) System for transmission of a signaling signal by the electrical network comprising a transmitter injecting into the electrical distribution network signaling signals, consisting of a carrier modulated in frequency by a tone signal with voice frequency, as long as a given condition is (or is not) fulfilled and no longer injecting any signal when this condition is not (respectively is) fulfilled, receivers delivering a control signal when they no longer receive any signaling signal, characterized in that it further comprises n repeaters receiving the signaling signals transmitted by the transmitter or other repeaters among these n repeaters and which deliver another signaling signal consisting of a carrier modulated in frequency by a signal of tone, the first repeater RE1 awaiting the end of the transmission, by the transmitter (8), of the first signaling signal F1, constituted by the modulation of a e first carrier pl by a first tone signal ql, and in turn transmitting a second signaling signal F2, consisting of a second carrier p2, of the same frequency as the first carrier pl, modulated by a second tone signal q2 different from the tone signal ql, the second repeater RE2 waiting for the end of the transmission of the second signaling signal F2 to transmit in turn a third signaling signal F3, consisting of a third carrier p3 frequency modulated by a third tone signal q3 different from the other tone signals ql and q2, and so on until a last REn repeater, waiting for the end  e of a signaling signal Fn by a penultimate repeater,  e in turn emits a (n + l) e signaling signal Fn + 1, consisting  e of a carrier pn + 1 modulated in frequency by a (n + 1) tone signal qn + l different from the tone signals ql to sb, the emissions of the signals F1 to Fn + 1 not overlapping in time, and in that the receivers (9) are designed to receive all the signals F1 to Fn + 1 emitted by the transmitter (8) and the n repeaters (18) and deliver a control signal only when they no longer receive, for a predetermined time T, no signaling signal.  2) system for transmitting a signaling signal according to claim 1, characterized in that the signaling signal emitted by the transmitter and those emitted by the repeaters have voltages whose value is of the order of 0.7 volts .  3) Security system comprising a detector of a security condition and security devices, characterized in that it further comprises a transmission system according to claim 1 or 2, the detector controlling the transmitter so that it sends the signaling signal F1 when a safety condition is fulfilled, and it does not emit any signal when this safety condition is no longer fulfilled, the receivers delivering a command signal to the safety devices when they do not no longer receive any signaling signal FI to Fn + 1 from the transmitter (8) and / or the repeaters (18) for a predetermined time.  4) Security system for a controlled mechanical ventilation installation consisting of exhaust ducts (1) for combustion gases from boilers (6) from premises in a building, ducts connected to a fan (4) sucking these gases and the delivering to the outside, comprising a detector (10) for correct operation of the fan (4) and contacts (14) controlling the start / stop of each boiler (6), characterized in that it further comprises a system of transmission according to claim 1 or 2, the detector (10) controlling the transmitter (8) so that it emits the signaling signal F1 when the operation of the fan (4) is normal, and that it emits no signal when this operation is no longer normal, the receivers (9) delivering a control signal so that the contacts (14) stop the boilers (6) when they no longer receive any signaling signal F1 to Fn + 1 of the transmitter (8) and / or repeaters (18) from a predetermined time T.