저압용 전기전자부품의 절연시험을 위한 부분방전 측정시스템의 설계 및 제작

Abstract

This thesis deals with the design and fabrication of a partial discharge(PD) measurement system to evaluate dielectric performance of low-voltage electrical and electronic components. The system consists of a test voltage source, a coupling network with a discharge free capacitor and detection impedance, a low-noise amplifier, and a data acquisition(DAQ) device.

Low cutoff frequency of the detection circuit was set at 1MHz(-3dB) to attenuate AC voltage by -270dB and to pass discharge pulses only without any distortion. A shielding enclosure of Ni-Cu double structure and a high voltage filter with a high cutoff frequency of 570Hz were designed to get a better measurement condition against radiation and conduction noises from the outside.

Also, we designed a measurement software based on the LabVIEW programming tool. The software analyzes PD parameters such as sensitivity, apparent charge and frequency of PD pulse, discharge inception voltage(DIV), and discharge extinction voltage(DEV).

The sensitivity of the system calibrated by a standard pulse injection was 33.8mV/pC for photo-couplers, and 31.3mV/pC between primary windings and core, and 27.6mV/pC between primary and secondary windings for isolation transformers, respectively.

From the experimental results, it was confirmed that the proposed PD measurement system detects PD pulses over 0.3pC in photo-couplers and estimate dielectric performance of low-voltage electrical and electronic components.