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US 7,443,308 B2Granted
Enhanced AC immunity in ground fault detection
AssigneeADC DLS Systems, Inc.
InventorsWilliam J. Fox, Michael Carter
Life of this patent
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Abstract
A method for reducing the occurrence of false ground fault detections in a central office terminal is provided. The method includes generating a no-fault signal when no ground current is detected, delaying generation of a fault signal when ground current is detected at least for the duration of an expected pulse in AC induced signal, and when the ground current persists for a sufficient period, generating a signal indicating a fault condition.
Claims5
A central office terminal, comprising:
- at least one communication circuit adapted to communicate signals with at least one remote unit over at least one communication medium;
- a power supply adapted to provide power to the remote terminal over the at least one communication medium;
- a ground fault detection circuit, coupled to the power supply to detect ground fault current;
- an AC immunity circuit, coupled to the ground fault detection circuit, that is adapted to modify the output of the ground fault detection circuit to reduce the occurrence of false ground fault detections due to AC induction;
- and
- a processor, coupled to the power supply and the AC immunity circuit, that is adapted to determine when a ground fault occurs based on the signal from the AC immunity circuit.
3 more elements
Dependencies are inferred from the claim text.