POWER DIRECTION RELAY Russian patent published in 2003 - IPC

FIELD: electrical engineering. SUBSTANCE: relay has series-connected intervening potential transformer and first threshold unit; series-connected intervening current transformer and second threshold unit; first AND gate whose first and second inputs are connected to HIGHER outputs of first and second threshold units, respectively; second AND gate whose first and second inputs are connected to LOWER outputs of first and second threshold units, respectively; first reversing counter whose addition input is connected to output of first AND gate and subtraction input, to output of second AND gate; double-threshold comparator whose data input is connected to output of first reversing counter; final element whose input is connected to output of threshold unit; series-connected one-shot multivibrator, clock generator whose output is connected to third inputs of first and second AND gates, third AND gate whose second input is connected to HIGHER output of second threshold unit, second counter, memory register whose setting input is connected to one-shot multivibrator output, and higher and lower threshold levels setting unit whose outputs are connected, respectively, to setting inputs for upper and lower threshold levels of double-threshold comparator; series-connected pulse shaper whose input is connected to HIGHER output of first threshold unit and to second input of third AND gate, and OR gate whose second input is connected to setting input of first reversing counter and output, to 0 setting input of second counter, clocked circuit of memory register being connected to pulse shaper output. EFFECT: enhanced precision of relay. 2 cl, 1 dwg