High sensitive DCPD measurement and analysis system of high-voltage storage capacitor

Partial discharge detection under DC is an appropriate method for insulation condition estimation. This paper presented a DCPD measurement and analysis system. System, characterized by high signal to noise ratio and strong ability for interference suppression, was composed with narrowband RLC balanced detection circuit, gain-stable amplifier and band-pass filter. Through trigger acquisition, DCPD signal was transferred to the computer and data were processed based on Δt analysis method in order to reflect characteristic parameters of PD signal by spectrum and fingerprint. Through the calibration by standard pulse generator, sensitivity of whole system reached 2pC which is enough to detect PD current in storage capacitor. Based on this measurement and analysis system, measurement for high-voltage storage capacitor with typical defects would be conducted and the results effectively reflected relationship of PD parameters. Therefore, the establishment of this system settled a good basis for defect types recognition and aging degree estimation of capacitors.