Electronic fault detector for variable frequency ac systems and circuit breaker incorporating same
First Claim
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1. A fault detector for a variable frequency ac electric power system comprising:
- current detector detecting variable frequency ac current flowing in the variable frequency ac electric power system;
processing means for processing half cycles of the variable frequency ac current for indications of a fault;
wherein the processing means comprises measuring means measuring the magnitude and corresponding period of selected half cycles of the variable frequency ac current and signal generating means generating a fault signal as a function of the magnitude and corresponding period of the selected half cycles of the variable ac current; and
wherein the measuring means including means detecting zero crossings of the variable frequency ac current for determining the corresponding period.
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Abstract
A fault detector processes half cycles of current in variable frequency ac power systems by weighting half cycle magnitude values by the period of the half cycle. Time attenuated accumulations of the weighted half cycle peak values exceeding a first threshold for short delay protection, and of weighted positive differences between the peak values of successive half cycles and the preceding half cycles for a selected period of time after a peak value exceeds a second threshold for arc faults, generate trip signals when they reach specified levels.
21 Citations
1 Claim
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1. A fault detector for a variable frequency ac electric power system comprising:
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current detector detecting variable frequency ac current flowing in the variable frequency ac electric power system;
processing means for processing half cycles of the variable frequency ac current for indications of a fault;
wherein the processing means comprises measuring means measuring the magnitude and corresponding period of selected half cycles of the variable frequency ac current and signal generating means generating a fault signal as a function of the magnitude and corresponding period of the selected half cycles of the variable ac current; and
wherein the measuring means including means detecting zero crossings of the variable frequency ac current for determining the corresponding period.
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Specification
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Current AssigneeEaton Intelligent Power Limited (Eaton Corporation PLC.)
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Original AssigneeEaton Corp. (Wisconsin) (Eaton Corporation PLC.)
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InventorsParker, Kevin Lynn
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Primary Examiner(s)Sircus, Brian
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Assistant Examiner(s)Demakis, James A.
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Application NumberUS10/135,591Publication NumberTime in Patent Office805 DaysField of Search361/93.1, 361/111, 361/115, 361/88, 361/78, 361/42US Class Current361/93.1CPC Class CodesH02H 1/0015 Using arc detectorsH02H 3/0935 the timing being determined...H02H 3/44 responsive to the rate of c...
