Partial Discharge Detection under Impulse Voltage Application by Acoustic Emission Sensors in Oil/Pressboard Composite Insulation System

Power transformers use an oil and pressboard composite system. In order to improve the dielectric performance or downsize the apparatus, it is essential to sophisticate partial discharge (PD) detection methods as well as to clarify PD characteristics under impulse voltage application. Various kinds of PD detection method have been proposed and developed by many researchers over a long period. For example, ultra high frequency (UHF) electromagnetic waves induced by PD are often used for PD detection, due to their high sensitivity. However, most of these researches were conducted for PD detection under AC voltage application or monitoring the condition of the apparatus and it is quite difficult to detect in the case of an impulse voltage withstand test on an actual power transformer, because…