Arc fault circuit detector having two arc fault detection levels
First Claim
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1. An arc fault protection device, protective of an electrical distribution system having a load, comprising:
- a sensor for sensing arc fault signatures in the presence of unwanted arc fault mimicking noise;
a load current threshold detector; and
first and second filters for distinguishing arc fault signatures from said unwanted arc mimicking noise having first and second sets of characteristics, respectively, wherein said first filter is enabled if a load current is below said load current threshold, and said second filter is enabled if said load current is above said load current threshold.
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Abstract
An arc fault protection device uses two detection levels for detecting both parallel and series arc faults. When a sensed load current is below a predetermined level, a first set of characteristics indicative of a series arc fault are compared to a sensed di/dt signal. When the sensed load current exceeds the predetermined level, a second set of characteristics indicative of a parallel arc fault are compared to the sensed di/dt signal. This approach allows more time to evaluate a potential series arc fault than is permitted when evaluating a potential parallel arc fault.
121 Citations
41 Claims
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1. An arc fault protection device, protective of an electrical distribution system having a load, comprising:
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a sensor for sensing arc fault signatures in the presence of unwanted arc fault mimicking noise;
a load current threshold detector; and
first and second filters for distinguishing arc fault signatures from said unwanted arc mimicking noise having first and second sets of characteristics, respectively, wherein said first filter is enabled if a load current is below said load current threshold, and said second filter is enabled if said load current is above said load current threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An arc fault protection device, protective of an electrical distribution system having a load, comprising:
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a sensor for sensing arc fault signatures in the presence of unwanted arc fault mimicking noise;
a load current threshold detector; and
first and second filters for distinguishing arc fault signatures from said unwanted arc mimicking noise having first and second sets of characteristics, respectively;
wherein said first filter is enabled if a load current is below said load current threshold, and said first and second filters are enabled if said load current is above said load current threshold. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. An arc fault protection device, protective of an electrical distribution system having a load, comprising:
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a sensor for sensing arc fault signatures in the presence of unwanted arc fault mimicking noise;
a first load current threshold detector;
a second load current threshold detector; and
first and second filters for distinguishing arc fault signatures from said unwanted arc mimicking noise having first and second sets of characteristics, respectively;
wherein said first filter is enabled if a load current exceeds said first load current threshold, and said second filter is enabled if said load current exceeds said second load current threshold and wherein said first load current threshold detector is set below said second load current threshold detector; and
said first and second filters are disabled if said load current is below said first load current threshold.- View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. An arc fault protection device, protective of an electrical distribution system having a load, comprising:
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means for sensing arc fault signatures in the presence of unwanted arc fault mimicking noise;
a load current threshold detector; and
first and second filter means for distinguishing arc fault signatures from said unwanted arc mimicking noise having first and second sets of characteristics, respectively;
wherein said first filter means is enabled if a load current is below said load current threshold, and said second filter means is enabled if said load current is above said load current threshold.
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28. An arc fault protection device, protective of an electrical distribution system having a load, comprising:
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means for sensing arc fault signatures in the presence of unwanted arc fault mimicking noise;
a load current threshold detector; and
first and second filter means for distinguishing arc fault signatures from said unwanted arc mimicking noise having first and second sets of characteristics, respectively;
wherein said first filter means is enabled if a load current is below said load current threshold, and said first and second filter means are enabled if said load current is above said load current threshold.
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29. An arc fault protection device, protective of an electrical distribution system which includes at least first and second conductors and having a load connected across said first and second conductors, comprising:
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detecting means for detecting a di/dt signal on one of said first and second conductors;
sensing means for sensing a load current of said electrical distribution system; and
determining means for determining whether said di/dt signal is indicative of noise, a parallel arc fault, or a series arc fault, wherein said determining means uses a first set of characteristics to determine whether said di/dt signal is indicative of noise, a parallel arc fault, or a series arc fault and a second set of characteristics to determine whether said di/dt signal is indicative of noise or an arc fault when an arcing current exceeds a rating of an overcurrent protection device protecting said electrical distribution system. - View Dependent Claims (30, 31, 32, 33, 34, 35)
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36. A method for protecting an electrical distribution system which includes at least first and second conductors and having a load connected across said first and second conductors, comprising the steps of:
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detecting a di/dt signal on one of said first and second conductors;
sensing a load current of said electrical distribution system; and
determining whether said di/dt signal is indicative of noise, a parallel arc fault, or a series arc fault, said step of determining using a first set of characteristics to determine whether said di/dt signal is indicative of noise or a high level arc fault and a second set of characteristics to determine whether said di/dt signal is indicative of noise or a low level arc fault, whereby said step of determining uses either said first set of characteristics or said second set of characteristics based on input received from said step of sensing. - View Dependent Claims (37, 38, 39, 40, 41)
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Specification