FIELD: electrical engineering; short-circuit protection of low-voltage circuits when signal is transmitted over communication lines. SUBSTANCE: when device output is energized, failure alarm 5 sets logic 1 across first AND gate 15 of control element 6. This signal enable passage of signal from ring counter 14 through first AND gate 15 to second input of control switch 10 and disconnects it. This builds up zero potential across output of D flip-flop 8 at device output. Device is disconnected thereby ensuring its serviceability under destabilizing conditions. EFFECT: improved reliability of circuit protection. 2 cl, 7 dwg
