No abstract

According to IEC60060-1, IEC60060-2 requirements, the large transformer should take impulse voltage test in site. However, this test is not performed in the field for the impulse voltage generator huge and difficult to operate. To solve this problem, IEC60060-3 propose using oscillating impulse voltage for equipment on-site impulse withstand voltage test. Oscillating impulse voltage has higher generation efficiency and close to the actual voltage waveform that electrical equipment bear. For the transformer, the oscillating impulse voltage can generated through inductive method. In order to study the generation of oscillating impulse voltage through inductive method for transformer, the simulation circuit is established using ATP soft and the oscillating switching impulse voltage characteristics is studied in this paper. The result show that the oscillating switching impulse voltage waveform that accordance with IEC requirements can be generated through inductive method for transformer.

Partial discharge (PD) detection is a technique widely used for high voltage equipment insulation condition assessment. The metal protrusion is a situation that often appear in transformer. Metal protrusion will cause the electric field concentration and lead to partial discharge. In this paper, PD characteristics in transformer oils are examined under AC conditions, using a needle-to-plane electrode system. The PD activity in transformer oil is confirmed as appearing in pulse burst form and the PD number and amplitude will increase with the applied voltage increase. The PRPD pattern display behavior typical of corona PD in oil.