FIELD: electrical engineering and power engineering for inserting multiphase devices in neutral. SUBSTANCE: device that can be used in lines with neutral grounded in any way has circuit set up of series-connected resistor with linear current-voltage characteristic connected to neutral of multiphase ac device, resistor with nonlinear current-voltage characteristic, and current sensor, as well as switching apparatus and automatic-control unit; rated voltage of switching apparatus is below that of multiphase device neutral and rated voltage of resistor with nonlinear current-voltage characteristic does not exceed that of switching apparatus. EFFECT: reduced power loss under normal conditions; reduced mass and size of device. 3 cl, 1 dwg
