Partial discharge testing of subsea insulation materials development of testing methods

Subsea installations on the sea bed at great depth require insulation materials with high reliability. Failures of such installations introduce difficult maintenance and high costs. This involves the need of reliable (insulation) materials and testing of such. The purpose of our activity is to build a test facility that can test both well-known and new insulation material samples as well as high voltage systems and apparatus. The qualification methods are based on existing international standards, with the aim of proposing and qualifying new QA and FAT tests for the subsea service environment. This paper presents some of the tests we have carried out on insulation materials. The experiments showed that the atmosphere is important; humidity introduces the risk of build up of a connection (solid bridge) between the electrode and insulation surface. High pressure reduces the area exposed to surface discharges and thereby increases the wear of the surface on that smaller area.