US 6,721,151 B2Granted

Ground fault interrupter

AssigneeMatsushita Electric Works, Ltd.

InventorsKiyoshi Goto, Yoichi Kunimoto, Yoshihisa Ishigami

Life of this patent

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Abstract

A ground fault interrupter including a zero-phase current transformer configured to detect unbalanced current flowing in electric lines. A switch is provided in the electric lines. A detection resistor is connected in parallel to the zero-phase current transformer and configured to convert current outputted from the zero-phase current transformer to voltage. A controller is configured to determine based on the voltage of the detection resistor whether an electric leak occurs and to open the switch when the controller determines that an electric leak occurs. At least one filter is provided between the detection resistor and the controller and is configured to remove high frequency elements in the voltage of the resistor. The at least one filter includes an input side resistor connected in series to the controller and configured to limit current input to the controller; and a capacitor connected in parallel to the controller.

Claims8

Dependent claims

A ground fault interrupter, comprising:

a switch provided in electric lines connecting an electric power source and an electric load;
a zero-phase current transformer configured to detect unbalanced current flowing in the electric lines;
a detection resistor connected in parallel to the zero-phase current transformer and configured to convert current outputted from the zero-phase current transformer to voltage;
a controller configured to determine based on the voltage of the detection resistor whether an electric leak occurs and configured to open the switch when the controller determines that an electric leak occurs;
at least one filter provided between the detection resistor and the controller and configured to remove high frequency elements in the voltage of the resistor, the at least one filter comprising:
an input side resistor connected in series to the controller and configured to limit current input to the controller;
and
a capacitor connected in parallel to the controller;
an additional current transformer configured to detect grounding;
and
an alternating-current electric source configured to supply current to the additional current transformer to energize the additional current transformer, the alternating-current electric source comprising:
a rectifier configured to rectify alternating-current;
and
an oscillator configured to generate alternating-current from the rectified alternating-current.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/808,152Filed 15 Mar 2001
Priority: JP 2000-07299215 Mar 2000
Published: US 2001/0036048 A11 Nov 2001
Granted: 13 Apr 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

H02H 3/33
Involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go…:…
H02H 1/04
Details of emergency protective circuit arrangements: arrangements for preventing response to transient abnormal conditions, e.g. to lightning or…
H02H 3/331
Using summation current transformers: responsive to earthing of the neutral conductor
H02H
Emergency protective circuit arrangements