| 摘要 |
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. <IMAGE>
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