DEVICE FOR PROTECTION OF THREE-PHASE ELECTRIC MOTOR AGAINST OPEN-PHASE MODE Russian patent published in 2010 - IPC H02H7/08 

FIELD: electricity.

SUBSTANCE: device comprises filter of negative sequence voltage, containing resistors, the first and second capacitors, two current reed relays, two current transformers and components included into responder - rectifying bridge, the third and fourth capacitors, additional resistor and threshold element, besides primary windings of current transformers are connected into two phase wires, to secondary windings there are windings of current reed relays connected, closing contacts of which are connected in parallel to resistors of negative sequence voltage filter, to output of which rectifying bridge is connected, to bridge output the following components are connected in parallel - the third capacitor, additional resistor, and via threshold element shunted with the fourth capacitor, actuating element, contact of which is shunted in circuit of magnetic starter coil, besides in phases of supply line there are three transformers installed, which convert current into voltage, and are connected to inlets of negative sequence voltage filter, accordingly.

EFFECT: improved reliability of device operation as a result of actuation in case of supply grid phase rupture downstream area of negative sequence voltage filter connection.

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