Low-Side Surges in Distribution Transformers

It was discovered in the 1980\´s that many distribution transformer primary winding failures were actually induced from the low-voltage winding. Transformer designers named this phenomenon "Low-side Surges". The IEEE PES Transformers Committee reached agreement on the subject and issued a position paper at the 1991 IEEE PES T&D Conference. Despite the widespread publicity this received at the time, low-side surge phenomena remain misunderstood and are unknown to many of the latest generation of distribution engineers. This paper describes the phenomena in practical terms. Data from distribution transformer failure studies are provided. A new tool for analyzing the phenomena is introduced