Condition Assessment of High Voltage Instrument Transformer Using Partial Discharge Analysis

Determining the incipient faults in high voltage apparatus is important because failure without warning can result in damage to adjacent equipment, personnel injures, customer dissatisfaction and disruption to economic activity. The failure of several high voltage instrument transformers during in-service prompted Tenaga Nasional Berhad (TNB) to identify more effective diagnostic tool to predict insulation breakdowns. The viability of partial discharge (PD) measurements in the field on instrument transformers is investigated. This paper presents the results of partial discharge tests that have been carried out under laboratory experiments and field measurement on high voltage instrument transformers.