CURRENT RELAY Russian patent published in 2002 - IPC

FIELD: electrical engineering; electronic relays. SUBSTANCE: relay has series-connected intervening current transformer, rectifier, and second threshold unit; first and second AND gates whose first inputs are connected, respectively, to HIGH and LOW outputs of second threshold unit; reversing counter whose addition and subtraction inputs are connected to outputs of first and second AND gates, respectively; third and fourth threshold units whose outputs are connected to inverting inputs of first and second AND gates, respectively; first threshold unit whose input is connected to reversing counter output; series-connected clock generator whose output is connected to second input of first AND gate and pulse frequency divider whose output is connected to second input of second AND gate; one-shot multivibrator whose output is connected to reversing-counter resetting input and to clock generator starting input; series-connected third AND gate and counter whose overflow output is connected to clock-generator stop input; series-connected pulse shaper that functions during negative differential signal across its input, its input being connected to output of first threshold unit and to first input of third AND gate whose second input is connected to output of pulse frequency divider, and OR gate whose second input is connected to output of one-shot multivibrator and output, to zero-setting input of counter; final element whose input is connected to output of first threshold unit. EFFECT: enhanced noise immunity. 2 cl, 2 dwg