Fire alarm system using delayed detectors - has evaluating circuit for false alarm recognition even after system reconnection

摘要

The system has device distinguishing between a continuous false alarm caused by a faulty detector, and a genuine alarm single. It has electronic detectors delivering an alarm signal with a delay (5) after their operating voltage connection, and a circuit interrupting the detector voltage at least once for a presettable period after a first alarm signal. When a detector voltage is reconnected, immediately present alarm signals are recognised by an evaluation device and signalled as false alarms. Alarm signals arriving with appropriate delay are recognised and retransmitted as a genuine signal.