FIRE ALARM Russian patent published in 1995 - IPC

FIELD: fire alarm system. SUBSTANCE: loop control unit 5, depending on resistance of loop, forms signals NORMAL or ALARM across outputs of threshold devices 5.4 and 5.5. Signal from output of unit 5 gets to processing unit 6 in which flip-flop 6.5 is set in initial position by means of integrating circuit 6.3, 6.4 at switching on. When normal condition of loop is disturbed, flip-flop 6.5 changes over and switches on generator 6.7 before switching off of device. Signalling relay 9 generates alarm signal which is transmitted to warning system. Under normal conditions relay 9 is de-energized and its contacts are closed. Under alarm conditions contacts of relay make and break periodically. If device is switched on for fire protection, contacts of signalling relay 9 remain closed when power is cut off, and signalling loop is kept under control of warning system. EFFECT: enhanced functional reliability of device. 3 cl, 1 dwg