Impulse Tests on Distribution Transformers Protected by Means of Spark Gaps

摘要

Distribution transformers in rural networks have to cope with transientovervoltages, even with those caused by the direct lightning strokes to the lines. In Finland the 24 kV network conditions, such as wooden pole lines, high soil resistivity and isolated neutral network, lead into fast transient overvoltages. Impulse testing of pole-mounted distribution transformers (equal to or less than 200 kVA) protected by means of spark gaps were studied. Different failure detection methods were used. Results can be used as background information for standardization work dealing with distribution transformers protected by means of spark gaps.