FIELD: electrical engineering. SUBSTANCE: method is based on individual extraction of modulus of each half-wave from alternating voltage of power circuits of protected rectifier set and in generation of signal for operation of protection by comparison of obtained moduli. Novelty of method consists in individual extraction of modulus of each half-wave of alternating voltage. Protective device has relay, two units for extraction of modulus of alternating voltage and two-polarity key. These components are connected in accord with diagram of half-wave rectification with doubling of voltage. EFFECT: simplified design. 4 cl, 2 dwg
