FIELD: electrical engineering. SUBSTANCE: gear to protect three-phase semiconductor converter against overvoltage fed with voltages of valve windings of converting transformer shifted through 120 electrical degrees has three protective windings put on magnetic circuit of converting transformer and connected according to star circuit. Gear is inserted with three-phase rectifier built on bridge circuit, two dischargers with spark gaps and two damping resistors. Like leads of first and second protective windings are connected in common point with unlike lead of third protective winding, isolated leads of protective windings are connected to leads of alternating current of three-phase rectifier. First leads of damping resistors are linked through discharges with spark gaps to unlike leads of direct current of three-phase rectifier bridge. Second leads of damping resistors are connected to tied-up leads of protective windings through output lead of one of valve windings of converting transformer. EFFECT: enhanced protective capabilities of gear. 5 cl, 4 dwg
