Coil current regulator with induced flux compensation in an electromagnetic contactor system
AssigneeWestinghouse Electric Corp.
InventorsRick A. Hurley, Mark E. Innes
Life of this patent
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Abstract
The coil holding current of a contactor is regulated to the lesser of two measurements of coil current during each cycle of the full-wave rectified control voltage to compensate for induced flux in the coil generated by load current through the main contacts of the contactor, thereby preventing uncontrolled drop out of the contactor.
Claims18
An electrical contactor having separable contacts, an electromagnet coil controlling opening and closing of said separable contacts to control a flow of load current therethrough, coil energizing means gating pulses of full wave rectified ac voltage to said electromagnet coil to close said separable contacts, and regulating means delaying gating of said pulses of full wave rectified ac voltage to said electromagnet coil to regulate coil holding current maintaining said separable contacts closed, and including means adjusting regulation of said coil holding current to compensate for flux induced in said coil by said load current.
A method of operating an electrical contactor having separable contacts and an electromagnet controlling opening and closing of said separable contacts to switch a flow of load current therethrough, said method comprising the steps of:
- gating pulses of rectified ac voltage to a coil of said electromagnet to close said separable contacts;
- regulating holding current in said coil once said separable contacts are closed by selectively delaying gating of said pulses of rectified ac voltage to said coil, and
- adjusting said regulating holding current to compensate for flux induced in said coil by said load current.
Dependencies are inferred from the claim text.