Measurement errors of a capacitive voltage transformer (CVT) are relevant to its equivalent\nparameters for which its capacitive divider contributes the most. In daily operation, dielectric aging,\nmoisture, dielectric breakdown, etc., it will exert mixing effects on a capacitive dividerââ?¬â?¢s insulation\ncharacteristics, leading to fluctuation in equivalent parameters which result in the measurement error.\nThis paper proposes an equivalent circuit model to represent a CVT which incorporates insulation\ncharacteristics of a capacitive divider. After software simulation and laboratory experiments,\nthe relationship between measurement errors and insulation parameters is obtained. It indicates\nthat variation of insulation parameters in a CVT will cause a reasonable measurement error. From\nfield tests and calculation, equivalent capacitance mainly affects magnitude error, while dielectric\nloss mainly affects phase error. As capacitance changes 0.2%, magnitude error can reach âË?â??0.2%.\nAs dielectric loss factor changes 0.2%, phase error can reach 5. An increase of equivalent capacitance\nand dielectric loss factor in the high-voltage capacitor will cause a positive real power measurement\nerror. An increase of equivalent capacitance and dielectric loss factor in the low-voltage capacitor\nwill cause a negative real power measurement error.
Loading....