Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
2006-09-05
2006-09-05
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C702S065000, C702S066000, C702S067000
Reexamination Certificate
active
07103485
ABSTRACT:
A method for preventing the unwanted maloperation of a protective relay system that is caused by the imprecise detection of an actual secondary current value resulting from a measured secondary current being distorted comprises the steps of calculating difference values for sampled secondary currents; comparing absolute values of the difference values with a predetermined critical value, and determining a saturation starting moment of a current transformer when one of the absolute values exceeds the predetermined critical value; obtaining a magnetizing current at the saturation starting moment using the difference values if the saturation starting moment is determined, and obtaining a magnetic flux value in a steel core of the current transformer from a magnetization curve using the magnetizing current; calculating a magnetic flux value at a time after the saturation starting moment using a secondary current value measured at that time and the magnetic flux value obtained at the saturation starting moment so as to obtain a secondary current value consistent with a current transformation ratio at that time; obtaining a magnetizing current at that time from the magnetization curve using the magnetic flux value calculated at that time; and obtaining the secondary current value consistent with the current transformation ratio by adding the obtained magnetizing current and the measured secondary current value.
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Kang Sang-Hee
Kang Yong-Cheol
Lim Yi-Jae
Hoff Marc S.
Myongji University
Suarez Felix
The Webb Law Firm
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