On-site dielectric loss measurements of 500 kV circuit-breaker capacitors under high voltage

Measurement of the capacitance and dielectric loss of the circuit-breaker capacitor is a very important task to assure safe operation of the circuit breaker. However, due to serious electric disturbance to the site measurement, more and more dielectric losses of 500 kV circuit-breaker capacitors appear over normal value under 10 kV testing voltage according to the CSG preventive trial standard. To solve problems mentioned above, we studied the shielding effect to electric disturbance when a testing power supply of different frequency from 50 Hz was used, and studied the dielectric loss variation of circuit-breaker capacitor with the applied testing voltage. By the improved testing method, we proposed two main programs for on-site dielectric loss measurement and analyzed their application situations. Moreover, we got the results of capacitance and dielectric loss measurements of circuit-breaker capacitors in Liudong transformer substation. The results showed that the improved measuring method was effective.