FIELD: electrical engineering. SUBSTANCE: invention relates to technical electric safety aids and is meant for protection against injuries by electric current of three-phase electric installations with operational voltage up to 1000 V. Device includes magnetic starter 9, buttons 10, 11, voltage amplifier 13, transformer 14 of current of zero sequence, light indicator, 15, terminals 6 on frames of electric equipment, four resistor elements 17, 18, 19,. New elements are terminals and tester 20 composed of two circuits formed by diodes 21, 22, 1, resistors 21.2 and 22.2 and capacitors 21.3 and 22.3, two voltage relays 23, 24, threshold 25 and key 26 elements, light indicator 27, buttons 24.2 and 28. If after first switching on of starter 9 test of voltage by pressure on button 28 is not conducted then growing voltage of capacitor 21.3 will reach voltage of switching over of resistor 26 which will switch on. After this relay 23 switches on under action of voltage of capacitor 23.1 and breaks contact of relay 23.1 de-energizing coil of starter 9. It will switch off and de-energize load and tester 20. EFFECT: increased operational safety. 2 cl, 1 dwg
