US 4,063,299 AGranted

Magnetically latched ground fault circuit interrupter

AssigneeEagle Electric Mfg. Co., Inc.

InventorRonald G. Munroe

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Abstract

A ground fault circuit interrupter (GFI) in which a load circuit is energized through a normally closed magnetically latchable circuit breaker. When no fault exists that is of sufficient magnitude to actuate the GFI, the latching coil of the circuit breaker is ineffective, whereby the circuit breaker remains closed. The coil is connected to the amplified DC output of a ground fault sensing circuit and is energized in a certain sense to open the circuit breaker upon the occurrence of a fault, the circuit breaker then being magnetically latched open. A capacitor is continuously DC charged in a certain sense by the AC supply line through a rectifier. To reset the circuit breaker the capacitor is selectively connected across the coil to discharge a pulse of a sufficient magnitude in a proper sense to reversely energize the coil enough to release the magnetic latch and allow the circuit breaker to reclose. The GFI is tested by closing a circuit that simulates a fault of the low magnitude which is to be sensed. Where additional circuits are protected by the same GFI they may be provided with resetting and testing equipment that are slaved to the GFI.

Claims16

Dependent claims

A GFI protected circuit comprising:

A. an AC line input including a live lead and a neutral lead,
B. a branch circuit including a live lead and a neutral lead,
C. a circuit interrupter between the line input and the branch circuit,
D. a sensor which, responsive to a fault of at least a predetermined magnitude, will generate an electric signal,
E. a rectifier energized from a live lead and a neutral lead and having a DC output,
F. an amplifier powered by the rectifier and having an output, the electric signal being fed to the amplifier,
G. a normally open switch having a control terminal connected to the amplifier output, the switch closing upon application to the control terminal of an amplifier output corresponding to a fault of at least said predetermined magnitude and thereupon supplying a DC current of a predetermined polarity,
H. said circuit interrupter including a remanent magnetic latching means and means biasing the interrupter closed,
I. said latching means being actuated by flow of current therethrough upon closure of the switch, said latching means remaining closed by remanent magnetization upon opening of the circuit interrupter and consequent deactuation of the latching means and opening of the switch,
J. an electric energy storing means,
K. means to charge said electric energy storing means in a predetermined sense,
L. releasing means to reduce the remanent magnetization of the latching means and, when actuated, to disable the latching means and permit the biasing means to close the circuit interrupter, and
M. a normally open reset switch that, upon closure, discharges the energy storing means to the releasing means in a sense to reduce the remanent magnetization of the latching means.

10 more elements

Dependencies are inferred from the claim text.