Publikasjoner og ansvarsområder
Partial discharges in liquid embedded power electronics: Effects of pressure and liquid nature under negative pulse voltage stress
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 p...
Electrocoalescence III : staus and summary report from activities
Liquid insulation of IGBT modules: Long term chemical compatibility and high voltage endurance testing
To facilitate operation of power electronics for subsea operation at ambient pressure components have to be submerged in a liquid. Equipment and schemes for testing of long term properties have been developed. Several techniques were used to investigate compatibility between a silicone gel and vario...
A novel bench size model coalescer: Dehydration efficiency of AC fields on water-in-crude-oil emulsions
We describe herein the design of a small AC electrostatic model coalescer for investigating coalescence efficiency of water in oil emulsions. The function of the model coalescer is tested on emulsions with different water cuts. In the coalescer, coalescence takes place in a couette flow in the bulk ...
Transformer Windings Ageing, diagnosis and asset management. Version 4
This report addresses state of the art in the field of transformer ageing and diagnostics, with emphasis on advising end-users on transformer asset management and on transformer specification. The basis is results from two projects on laboratory studies on ageing of mineral oil impregnated cellulose...
Influence of fast rise voltage and pressure on partial discharges in liquid embedded power electronics
Experimental study of electrocoalescence of water drops in crude oil using near-infrared camera
Results are presented concerning the influence of an applied electric field on the coalescence of a water droplet with a much bigger water drop, both drops being immersed in a crude oil. This original study of electrocoalescence in crude oil was performed through high-speed optical observations, usi...
Effects of spatial restriction on streamers in white oil
Streamer propagation guided within PTFE tubes were investigated in an 8 cm point-plane gap in white oil. Both positive and negative polarities were studied with a near step voltage of 50-400 kV. Streamers in a free volume were compared with those in tubes. Within tubes, branching of streamers is sup...