FIELD: electrical engineering; surge and phase-failure protection of high-voltage lines, including auxiliary supply systems of thermal power stations. SUBSTANCE: grounding connection has nonlinear resistors assembled into three-legged star whose legs are connected to line phases; linear resistor is connected between neutral and ground. Connected in series with linear resistor is circuit set up of switching device and current transformer whose secondary winding is coupled with relay protective gear that functions to turn off switching device. Additional nonlinear resistor is connected between neutral and ground; characteristics of main nonlinear resistor are chosen so that it sustains phase voltage for unlimited time while characteristics of additional resistor are selected so that line voltage may be applied for unlimited time to series-connected main and additional nonlinear resistors. Vacuum switch is used as switching device. EFFECT: improved ground fault protection and surge voltage restriction which raises reliability of high-voltage line. 4 cl, 1 dwg
