Discharge detection in high-voltage power transformers

The paper presents the special problems involved in the detection of discharges within high-voltage power transformers. This is followed by a review of the various location techniques being developed in different parts of the world. Both electrical and ultrasonic methods are considered. It is concluded that a routine test is not yet possible, but suggestions are made regarding the relationship between any such measurement and high-voltage insulation tests. It is emphasised that further information of discharge values obtained under prescribed conditions is essential before acceptance levels can be seriously discussed. Again, a test procedure is suggested. Comment is made on the suitability of existing discharge-detection equipment for measurements on transformers. Evidence indicates that a change might be desirable, possibly in association with a location technique. Finally, it is hoped that the paper will help produce a fuller discussion of the real problems involved in transformer-discharge detection, and perhaps lead to the crystallising of the many and varied ideas which have developed since the previous UK joint publication on the subject.