FIELD: electrical engineering, test of serviceability of maximum-current release devices of automatic switches. SUBSTANCE: technical result of invention consists in provision of separate test of all key units of maximum-current release device built into automatic switch ( of control unit, current pickups and actuating electromagnet ) and in complex test of functioning of maximum-current release device under all forms of emergency conditions in protected network including overloads, single-phase short- circuits to ground and interphase short-circuits both under condition of current short- circuit and under condition of short-circuit behind normally loaded switch. Device testing serviceability of AC overcurrent protection has network power supply source, rectifiers, switches, resistors, capacitors, operational amplifier, light-emitting diode indicator, connector for connection to tested protection. EFFECT: widened range of tested conditions. 1 cl, 2 dwg
