POWER SUPPLY PROTECTION UNIT ALARM Russian patent published in 2002 - IPC

FIELD: electrical engineering; protective gear operation alarm in power supply. SUBSTANCE: operation of self-resetting fuse 1 makes dc or ac operating voltage pass through current-limiting resistor 2 and rectifier 3 to input control circuit of optocoupler 4 which drives it in conduction. Signal picked off optical output of optocoupler 4 is inverted in first inverter 5 and changes flip-flop 6 over to other stable state. Same signal lights up red light-emitting diode 14 in display unit 7 upon passing through third inverter 12 and first AND gate 13 and green light-emitting diode 16 goes out. Signal memorizing operation of fuse 1 goes from output of flip-flop 6 to control input of pulse generator 9 and from inverting output of flip- flop 6, to input of switching unit 11 thereby turning on alarm relay and transmitting message about operation of self-resetting fuse 1 to communication line. Signal picked off pulse generator 9 is passed through second inverter 10 to second inputs of first and second AND gates 13, 15. In the process red light-emitting diode 13 starts flickering at frequency of pulse generator 9. In case of spontaneous reset of fuse 1 (upon recovery of load resistance) green light-emitting diode comes on and red light-emitting diode 14 goes out. However green light-emitting diode flickers to indicate that self-resetting fuse 1 has operated. Alarm relay turn-on signal is still applied across output of switching unit 11. Short-time pushing of RESET button 8 placed device in initial position. EFFECT: enhanced reliability of monitoring fuse operation. 2 cl, 1 dwg