Ground fault circuit interrupter and method
First Claim
1. A device configured to dynamically correct offsets associated with an AC power system that includes a line conductor, a neutral conductor, and a transformer, the device comprising:
- an offset correction circuit having first and second inputs and first and second outputs, the offset correction circuit comprising one of a chopper circuit or an auto-zeroing circuit;
a first amplifier having first and second inputs and an output, the first and second inputs coupled to the first and second outputs of the offset correction circuit, respectively, and the output of the amplifier coupled to the second input of the offset correction circuit;
a signal generator switchably coupled to the first input of the offset correction circuit; and
a bias generator switchably coupled to the first input of the offset correction circuit.
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Accused Products
Abstract
A method and circuit for dynamically correcting offsets associated with an AC power system. In an embodiment, a first offset current generated in response to a ground to neutral fault stimulus is decreased and a second offset current generated in response to a differential fault stimulus is decreased. In another embodiment, the circuit includes an offset correction circuit that has one of a chopper circuit or an auto-zeroing circuit. An amplifier is connected to the offset correction circuit and an output connected to the offset correction circuit. A signal generator is switchably coupled to a first input of the offset correction circuit and a bias generator is switchably coupled to the first input of the offset correction circuit.
65 Citations
15 Claims
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1. A device configured to dynamically correct offsets associated with an AC power system that includes a line conductor, a neutral conductor, and a transformer, the device comprising:
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an offset correction circuit having first and second inputs and first and second outputs, the offset correction circuit comprising one of a chopper circuit or an auto-zeroing circuit; a first amplifier having first and second inputs and an output, the first and second inputs coupled to the first and second outputs of the offset correction circuit, respectively, and the output of the amplifier coupled to the second input of the offset correction circuit; a signal generator switchably coupled to the first input of the offset correction circuit; and a bias generator switchably coupled to the first input of the offset correction circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A device configured to dynamically correct offsets associated with an AC power system that includes a line conductor, a neutral conductor, and a transformer, the device comprising:
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an offset correction circuit having a plurality of input terminals and a plurality of output terminals, the offset correction circuit comprising one of a chopper circuit or an auto-zeroing circuit; a first amplifier having first and second inputs and a plurality of outputs, the first and second inputs coupled to first and second output terminals of the plurality of output terminals of the offset correction circuit, respectively, and a first output of the plurality of outputs of the amplifier coupled to a first input of the plurality of input terminals of the offset correction circuit; a first switch having a control terminal, a first conduction terminal, a second conduction terminal, and a third conduction terminal, the first conduction terminal coupled to the a second input terminal of the plurality of input terminals of the offset correction circuit; a signal generator coupled to the second conduction terminal of the first switch; a bias generator coupled to the third conduction terminal of the first switch; a first detector having an input terminal and an output terminal, the input terminal of the first detector coupled to a second output of the plurality of outputs of the first amplifier; and a control circuit having a plurality of inputs and a plurality of outputs, a first output of the plurality of outputs of the control circuit coupled to the control terminal of the first switch. - View Dependent Claims (15)
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Specification