Test Method for HSC Standard Capacitor

HIMALAYAL - SHANGHAI - CHINA

HSC standard capacitor is commonly applied in high voltage test, mainly as external standard capacitor or for judgment of measurement error of high voltage dielectric tan delta bridge. The low voltage end of some HSC standard capacitor can be divided into several dielectric tap positions in utilization for dielectric tan delta bridge calibration. Capacitance amount to approximate 50pF, tgδ approximately <0.05%. This instrument isn’t a real three-terminal capacitor, easily damped, which will cause dielectric error.

I. Tangent

tgδ may appear minus value occasionally under 10kV voltage and will normalize if voltage reduced to 3kV, this is caused by internal damp. Replace moisture-proof agent or take out the internal capacitor core and dry it under the sun.

II. Inversed wiring

Capacitance and tgδmeasured with inversed wiring are slightly larger than the value measured with tangent, this is caused by influence of stray capacitance from inversed wiring.

III. Misoperated inversed wiring

While operating HSC inversed wiring, many habitually connect and ground the low voltage end and the shielding end in short circuit, rise voltage to the high voltage end and start measuring, which leads to an outcome of 58pF capacitance with 8pF capacitance rise. The reason for that is after connecting and grounding the low voltage end to the shielding end in short circuit, capacitance of the high voltage end towards shielding end is added through parallel connection causing capacitance rise. Therefore this method isn’t appropriate for inversed wiring.