Arc fault detector device with two stage arc sensing
First Claim
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1. An arc fault detector comprising:
- a first sensor responsive to the rate of change of current with respect to time in a circuit being protected, said first sensor generating a first signal;
a second sensor responsive to the magnitude of current flowing in said circuit being protected, said second sensor generating a second signal; and
a detector connected to the first sensor and the second sensor and responsive to the sum of the first signal and the second signal for generating an arc fault signal whenever the sum exceeds a preselected value;
in which the second sensor comprises a section of a line of a circuit being protected, having a resistance thereacross, for producing a voltage signal when an arc is present, and the detector is connected to receive the voltage signal from the section.
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Abstract
An arc fault detector for detecting an arc fault in electric power lines includes a two stage arc sensor. The first stage is a current transformer designed for high sensitivity to arc faults but which may saturate and lose detection capability during arc currents at 75A and higher. The second arc fault sensor, which does not saturate, stage senses the voltage across the impedance of the primary of the current transformer, or senses the voltage across the resistance of a section of the load carrying bus which forms the connection through the detector device, or of both, during an arc fault.
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Citations
12 Claims
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1. An arc fault detector comprising:
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a first sensor responsive to the rate of change of current with respect to time in a circuit being protected, said first sensor generating a first signal;
a second sensor responsive to the magnitude of current flowing in said circuit being protected, said second sensor generating a second signal; and
a detector connected to the first sensor and the second sensor and responsive to the sum of the first signal and the second signal for generating an arc fault signal whenever the sum exceeds a preselected value;
in which the second sensor comprises a section of a line of a circuit being protected, having a resistance thereacross, for producing a voltage signal when an arc is present, and the detector is connected to receive the voltage signal from the section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification