Capacitor coupled voltage transformers
OwnerForoozan Ghassemiinventor
Life of this patent
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Abstract
Accurate harmonic measurements on electrical power systems where the main instrument transformers are of the capacitor coupled voltage type (CVT type) is made possible by the provision of one or more current sensors (PQCS1, PQCS2). CVTs typically have a high voltage capacitor bank (CH) and a low voltage capacitor bank (CL). One or more current sensors (PQCS1, PQCS2) is/are positioned so as to measure capacitor current and from that the input voltage (Vin) of the CVT can be determined for each frequency.
Claims16
A method of determining parameters of the input voltage to a capacitor coupled voltage transformer which includes high voltage capacitor means and low voltage capacitor means connected across the input voltage, which comprises measuring the current flowing in at least one of said capacitor means, and from the measurements obtaining the required parameters of the input voltage.
A method according to any preceding claim, which comprises measuring the current flowing in each of said high voltage capacitor means and said low voltage capacitor means, obtaining from said measured values the voltages across each of said capacitor means, and summing the said voltages to obtain parameters of the total input voltage.
A method of retrofitting a capacitor coupled voltage transformer which has high voltage capacitor means and low voltage capacitor means arranged to be connected across an input voltage, whereby parameters of the input voltage can be determined, which comprises fitting the transformer with at least one current sensor to measure the current flowing in at least one of said capacitor means.
A capacitor coupled voltage transformer comprising high voltage capacitor means and low voltage capacitor means arranged to be connected across an input voltage, current sensor means arranged to sense the current flowing in at least one of said capacitor means, and measurement means arranged to provide from the sensed current values a measurement of parameters of the input voltage.
Dependencies are inferred from the claim text.