Partial discharges in narrow gaps on power electronic converter

The quest for power electronic converters to operate in a subsea pressurized environment that is completely filled with appropriate dielectric liquid brings about the need to study the insulation performance of liquid in the system while in operation. One of the critical regions for electrical insulation is the trench between metallization edges of the power converter. These regions are susceptible to high electric field stress and electrical discharges can be initiated around the region which could lead to insulation deterioration and eventually breakdown. This paper presents an experimental setup for the study of partial discharges (PDs) along the trench between metallization edges on printed circuit boards (PCBs) embedded in insulating liquid under sinusoidal high voltage sources of up to 20 kV_peak. The electric field distribution at the high field region was modelled and the electrical and optical measurements of the partial discharges obtained were correlated. PD activity around the triple region was evaluated and the rate at which pressure influenced PD events in the system is discussed.