FIELD: on-line checking of heavy-power transformer windings for condition. SUBSTANCE: device has three-phase power supply, three-phase circuit breaker, three-phase transformer under check, current transformers, potential transformers, resistive load, frequency meter, primary-to-secondary voltage reducing unit, voltage difference calculating unit, mean voltage calculating unit, current derivative determining unit, unit calculating voltage drop across resistor, resistance setting unit, inductance calculating unit, unit for reducing inductance to rated frequency, cycle mean inductance calculating unit, deviation determining unit, inductance setting unit, inductance deviation checking unit, and protective unit. EFFECT: provision for on-line monitoring and protecting transformer windings against deformation and other kinds of damage. 1 dwg
