Faulted circuit indicator
First Claim
1. A faulted circuit indicator for registering a fault in a power distribution circuit only when overcurrent in the circuit effects interruption thereof, comprising:
- means for detecting overcurrent in the power distribution circuit;
means for measuring the current in the distribution circuit during an examination time interval following the detection of overcurrent;
and means for providing a fault indication if the measured current, following the overcurrent detection, is less than a prescribed level, thereby evidencing interruption of the circuit and clearing of the fault.
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Accused Products
Abstract
Error-free, reliable registration of a fault in a power distribution circuit is achieved by a faulted circuit indicator that measures the current in the circuit after a discrete time delay following the detection of an overcurrent condition. A fault is registered only if the measured current is less than a prescribed level, evidencing that the overcurrent has operated a protection device (such as a fuse), upstream from the faulted circuit indicator, to interrupt the circuit and clear the fault. Hence, only actual (true) faults, resulting in circuit interruption and isolation of the fault, will be indicated, thereby precluding false registrations that may otherwise occur from non-faults such as transient currents, momentary overloads, inrush currents, and the like.
38 Citations
23 Claims
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1. A faulted circuit indicator for registering a fault in a power distribution circuit only when overcurrent in the circuit effects interruption thereof, comprising:
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means for detecting overcurrent in the power distribution circuit; means for measuring the current in the distribution circuit during an examination time interval following the detection of overcurrent; and means for providing a fault indication if the measured current, following the overcurrent detection, is less than a prescribed level, thereby evidencing interruption of the circuit and clearing of the fault.
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2. A faulted circuit indicator for registering a fault in response to overcurrent in an alternating current power distribution circuit only when the overcurrent causes a protection device, upstream from the faulted circuit indicator, to interrupt the circuit and clear the fault, comprising:
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sensing means for monitoring the current flowing through the power distribution circuit; overcurrent detecting means responsive to said sensing means for detecting an overcurrent condition; control means responsive to said sensing means and to said overcurrent detecting means for examining the current in the power distribution circuit during a predetermined examination time interval subsequent to the time at which an overcurrent condition is detected; and indicating means, controlled by said control means, for providing a fault registration only when the current examined during the predetermined examination time interval has an amplitude less than a prescribed level, thereby positively indicating that an actual fault exists and that the distribution circuit has been interrupted as a result of the overcurrent condition. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for registering a fault in a power distribution circuit only when overcurrent in the circuit effects interruption thereof, comprising the steps of:
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detecting overcurrent in the power distribution circuit; after the expiration of a given discrete time delay following the detection of overcurrent, measuring the current in the distribution circuit during a subsequent predetermined examination time interval; and thereafter providing a fault indication if the measured current during the predetermined examination time interval is less than a prescribed level, thereby evidencing interruption of the circuit and clearing of the fault.
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Specification