Statistical analysis of dielectric breakdown of liquid insulated printed circuit boards

For introducing power converters at ambient pressure at large sea depths, dielectric liquids are proposed as insulation for power electronic converters. This paper presents statistical analysis of short time tests of partial discharge and breakdown voltage on the trench between metallized edges of printed circuit boards (PCBs) embedded in in different dielectric liquids. Performance of Nytro 10XN, Midel 7131 and Galden HT230 were investigated. Investigations were done both for sinusoidal voltages and for positive fast transient square voltages. Galden as insulating liquid has the highest withstand voltage with higher breakdown voltage at low probability of failure. The overall evaluation shows that all the liquid samples possessed high dielectric strength that has the potential of providing sufficient insulation for subsea power converters. Coating the metal surfaces with thin layer of parylene increases the system reliability by reducing the effect of contaminations.