Application of On-line Partial Discharge Measurement for High Voltage Equipment in Thailand

Insulation monitoring and diagnosis is a condition-based maintenance and essential for an economic usage of high-voltage equipment. Appropriate monitoring and diagnosis before severe faults occurs makes it possible to control and operate a power system in a more reliable, effective, and sustainable way. Compared to other monitoring techniques such as chemical and thermal techniques, partial discharge (PD) monitoring seems to be the most promising methodology for detecting possible dielectric breakdown, aging and, ultimately, faults in power system components. PD is indeed an important indicator of an insulation condition in medium voltage (MV) and high voltage (HV) systems. The PD phenomenon is exhibited in various observable forms such as electrical, mechanical, optical and electromagnetic energies. The objectives of this paper were to present the application of on-line PD measurement and monitoring technology for the insulation condition assessment in medium and high voltage systems. The paper presents some of the sensor technology used to measure power cables, switchgear, transformers, and rotating machines for on-line PD. The paper also includes case studies of past experiences carried out by authors when using on-line PD measurement in various MV & HV assets in Thailand. Three cases studies are presented; generator, transformer and gas insulated switchgear. The efficiency and accuracy of on-line PD measurement was indicated by burn mark at equipment part as analyzed via partial discharge measurement.