FIELD: electrical power engineering, relay protection. SUBSTANCE: device includes current transformers 1 which output is connected to input of filter 2 of currents of zero sequence. Output of filter is linked to input of first operational amplifier 4 and input of amplitude detector 9. Output of amplitude detector is connected to first input of comparator 10 which second input is connected to source 3 of displacement current. Output of first operational amplifier is connected to resistor 6 of RS network. Common point of resistor 6 and capacitor 7 of RS network is linked to input of second operational amplifier 5 and to output of comparator 10 via isolation diode 7. Output of second operational amplifier 5 is connected to input of actuating element 8. EFFECT: enhanced accuracy of device under conditions of change of ambient temperature. 2 dwg
