DEVICE OF PROTECTION AGAINST LEAKAGE CURRENTS IN SHAFT ELECTRIC CIRCUITS Russian patent published in 2013 - IPC H02H3/17 

FIELD: electricity.

SUBSTANCE: device of protection against leakage currents comprises a unit of insulation monitoring and protective disconnection, a unit of detection and protective grounding of phase with damaged insulation, and also an additional unit of voltage comparison proportionate to voltage of neutral displacement sent from an additional AC winding placed in a compensating throttle with a reference one, and an additional relay impacted by this unit. Contacts of the additional relay are switched into the circuit of circuit breaker opening supplying voltage to the protected circuit, regardless of the position of contacts of the measurement relay of the unit of circuit insulation resistance monitoring, and into the circuit of relay winding control, providing for protective grounding of the grid phase with damaged insulation. In the unit of insulation monitoring and protective disconnection comprising a source of measurement current, a unit of its comparison with the reference one, a measurement relay, a unit to connect this source between phases of the protected circuit and earth is proposed to be made in the form of serially connected separating capacitor and compensating throttle, the AC winding of which is to be connected with zero point of secondary windings of the power transformer, and the contact of the measurement relay is to be connected into the circuit of breaker opening, through which the power transformer is supplied.

EFFECT: increased reliability and efficiency.

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