Method of an apparatus for detecting ground faults in electrical systems
First Claim
1. A method of detecting ground faults in ungrounded equipment having an electrical supply, the method comprising the steps of;
- connecting either side of the supply to a chassis ground terminal of the equipment;
impressing a voltage varying alternately between two predetermined values on the terminal relative to one side of the supply;
detecting and monitoring with respect to this side of the supply, the resulting potential between this side and the chassis ground, said potential varying between predetermined magnitudes in the absence of any ground leak; and
monitoring said potential, ground faults in the equipment being detectable by a change in magnitude of said varying potential;
establishing ground faults by changes in the magnitude of the varying potential; and
locating the faults with respect to the sides of the supply from variations to the upper and lower predetermined values.
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Accused Products
Abstract
A method of detecting ground faults in ungrounded equipment having an electrical supply. The method comprises the steps of:
Connecting either side of the supply to a chassis ground terminal of the equipment;
Impressing a voltage varying alternately between two predetermined values on the terminal relative to one side of the supply;
Detecting and monitoring, with respect to this side of the supply, the resulting potential between this side the chassis ground, said potential varying between predetermined magnitudes in the absence of any ground leak;
Monitoring said potential, ground faults in the equipment being detectable by a change in magnitude of said varying potential, establishing ground faults by changes in the magnitude of the varying potential and
Locating the faults with respect to the sides of the supply from variations to the upper and lower predetermined values.
Preferably the limits to the voltage will be a predetermined value and substantially zero.
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Citations
11 Claims
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1. A method of detecting ground faults in ungrounded equipment having an electrical supply, the method comprising the steps of;
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connecting either side of the supply to a chassis ground terminal of the equipment; impressing a voltage varying alternately between two predetermined values on the terminal relative to one side of the supply; detecting and monitoring with respect to this side of the supply, the resulting potential between this side and the chassis ground, said potential varying between predetermined magnitudes in the absence of any ground leak; and
monitoring said potential, ground faults in the equipment being detectable by a change in magnitude of said varying potential;establishing ground faults by changes in the magnitude of the varying potential; and
locating the faults with respect to the sides of the supply from variations to the upper and lower predetermined values. - View Dependent Claims (2)
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3. Apparatus for detecting ground faults in ungrounded equipment including a chassis and having an electrical supply, the apparatus comprising:
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a chassis ground terminal of the equipment connected to either side of the supply means for impressing a voltage variable alternately between two predetermined values on the terminal relative to one side of the supply; a voltage detector connected to measure varying potential between said side and the chassis ground; a monitor connected to the detector to indicate variations in the potential and a relay connected to the monitor connected to control the supply to the equipment. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11)
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Specification