Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1995-02-10
1996-12-24
Regan, Maura K.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
324520, G01R 2708
Patent
active
055876625
ABSTRACT:
Impedance of an energized electrical line which carries electrical current at a predetermined line frequency is nondistruptively measured at frequencies which are above and below the predetermined line frequency. A measurement current is generated at a measurement frequency between, for example, 10 Hz and 30 kHz for a 60 Hz line. The current generator is coupled to the energized electrical line by an isolating circuit which blocks only the predetermined line frequency and frequencies which differ from the predetermined line frequency by substantially less than the predetermined line frequency. For example, a notch filter may be used. A current sensor measures the line current in the energized line at the measurement frequency. A voltage sensor measures the line voltage in the energized electrical line at the measurement frequency. An analyzer determines impedance of the energized line at the measurement frequency. The measurement is repeated over a wide range of frequencies above and below the line frequency. Preferably, the current sensor and voltage sensor use the same current sensor to cancel errors. Improved nondisruptive line impedance measuring is thereby provided.
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Harris Matthew B.
Kelley Arthur W.
North Carolina State University
Regan Maura K.
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