FIELD: power supplies; relay protective gear for three-phase induction motors of hoisting and hauling mechanisms. SUBSTANCE: device functions to compare motor currents shifted in phase through angle 2π/3 under normal conditions and through angle π in case of phase failure in supply mains, and also to compare interphase voltages across motor terminals shifted in phase through angle 2π/3 under normal conditions and in case of phase failure and through angle approaching π in case of external interphase short circuits. EFFECT: improved reliability and speed of response. 2 dwg
