Process and device to determine malfunctioning detectors acting as current sinks in a danger signaling system

A process to determine malfunctioning detectors acting as current sinks in a danger signaling system which comprises a control centre and at least a two-wire signaling line joined thereto to which a multiplicity of detectors is connected wherein each detector has a capacitor for energy storage, a measuring resistor interposed in a wire, an evaluation device analyzing the voltage drop on the measuring resistor, an address memory, and a switch adapted to be controlled by the evaluation device between the wires, comprising the following process steps:

• the control centre cyclically emits voltage-modulated digital control and interrogation data to the detectors, and the detectors when interrogated by the control centre emit current-modulated digital data to the control centre;
• the detector saves a control signal in a malfunction memory if it does not receive any interrogation signal from the control centre within a preset interval;
• if no reply signal is received from a detector the control centre emits a voltage signal (a data word) by which the malfunction memories of the detectors capable of reception are occupied;
• the detectors measure their power input and compare it to the preset maximum;
• the control centre generates a voltage signal for closing the switches of all detectors with only the switches of the detectors being closed;
• the control centre subsequently provides an impressed current of a preset magnitude to the line;
• the evaluation device opens the switch if the power input does not exceed a preset maximum and the voltage dropping on the measuring resistor reaches a preset value,
• the detector next in succession also opens the switch if the voltage dropping on its measuring resistor reaches its preset value and the power input does not exceed the preset maximum, etc.;
• the control centre determines the detector the switch of which has remained closed at least temporarily.

A process to disconnect malfunctioning detectors acting as current sinks in a danger signaling system which comprises a control centre and at least a two-wire signaling line joined thereto to which a multiplicity of detectors is connected wherein each detector has a capacitor for energy storage, a measuring resistor interposed in a wire, an evaluation device analyzing the voltage drop on the measuring resistor, an address memory, and a switch adapted to be controlled by the evaluation device between the wires, comprising the following process steps:

• the control centre cyclically emits voltage-modulated digital control and interrogation data to the detectors, and the detectors when interrogated by the control centre emit current-modulated digital data to the control centre;
• if faulty data are received following an interrogation by the control centre this one emits a voltage signal (a data word) to the detectors for memorizing it as a malfunction signal in a malfunction memory;
• the power input of the detectors is measured and saved in a measured-value memory before, simultaneously or afterwards;
• the switch of the detector the malfunction memory of which is occupied and the power input of which exceeds a maximum is closed for the generation of a short-circuit current between the wires;
• the short-circuit current activates at least one short-circuit disconnecting member which breaks at least one wire of the signaling line.