Investigations of severe faults on 22–66 kV cast resin voltage measuring transformers in Norway

The paper is dealing with aging and fault developing processes in cast resin inductive voltage transformers. Utilities should pay particular attention to the procedures concerning ordering of transformers. The main goal is to assure that transformers have good quality when leaving the manufacturer. Most utilities do not consider major corrective actions or refurbishment of measuring transformers to be justifiable. Proposals for delivery tests beyond the routine tests are given.