FIELD: electrical engineering. SUBSTANCE: gear is designed for protection of synchronous generators against fault to ground in one point of excitation circuit. It includes source of superimposed voltage, selective current-to-voltage converter, connection filter, insulation resistance display unit, responding elements of sensitive and coarse steps of protection, unit of registration of fault of contact "brush-generator shaft", signal element. Gear is additionally fitted with source of superimposed voltage, selective converter, connection filter, first and second selective voltage-to-voltage converters, first and second units for determination of active and reactive components of equivalent resistances, first, second and third adders, first and second dividers, multiplier. Determination of equivalent resistance of insulation is accomplished by computation with tuning away from change of superimposed voltage, capacitance of excitation circuit and active resistance of connection filter. EFFECT: increased sensitivity and efficiency of protection. 2 cl, 1 dwg
