Method and apparatus for detecting ground fault current on a power line
First Claim
1. An apparatus for interrupting a ground fault, comprising:
- a fast response unit configured to produce a state change of a fast response output, based on a current on a power line, to indicate a ground fault at a first time after the ground fault occurs;
a slow response unit configured to produce a state change of a slow response output, based on the current on the power line, to indicate a ground fault at a second time after the ground fault occurs, the second time being later than the first time; and
a switch configured to be responsive to the state change of the fast and slow response outputs to interrupt the current on the power line in an event the state change in the fast or slow response output indicates a ground fault.
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Accused Products
Abstract
A ground fault interrupt (GFI) circuit detects and interrupts a ground fault, even in the presence of AC power induced currents. The GFI circuit can be used for power delivery between nodes in a network, such as from a central office to remote network equipment. The GFI circuit meets GFI specifications covering such an application. The GFI circuit detects rapid changes and slow rises in ground fault current. Safety features, such as intermittent interruptions of power on power lines in an event of a ground fault, are supported by the GFI circuit to protect field personnel. A digital processor may be used to implement aspects of the GFI circuit to support changes of or various operating environments.
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Citations
39 Claims
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1. An apparatus for interrupting a ground fault, comprising:
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a fast response unit configured to produce a state change of a fast response output, based on a current on a power line, to indicate a ground fault at a first time after the ground fault occurs; a slow response unit configured to produce a state change of a slow response output, based on the current on the power line, to indicate a ground fault at a second time after the ground fault occurs, the second time being later than the first time; and a switch configured to be responsive to the state change of the fast and slow response outputs to interrupt the current on the power line in an event the state change in the fast or slow response output indicates a ground fault. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An method for interrupting a ground fault, comprising:
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producing a state change of a fast response output, based on a current on a power line, to indicate a ground fault at a first time after the ground fault occurs; producing a state change of a slow response output, based on the current on the power line, to indicate a ground fault at a second time after the ground fault occurs, the second time being later than the first time; and interrupting the current on the power line in an event the state change of the fast or slow response output indicates a ground fault. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. An apparatus for interrupting a ground fault, comprising:
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means for producing a state change of a fast response signal, based on a current on a power line, to indicate a ground fault at a first time after the ground fault occurs; means for producing a state change in a slow response signal, based on the current on the power line, to indicate a ground fault at a second time after the ground fault occurs, the second time being later than the first time; and means responsive to the state change in the fast and slow response signals for interrupting the current on the power line in an event the fast or slow response signal indicates a ground fault.
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Specification