Secondary (low-side) surges in distribution transformers

A task force was formed in response to a proposal that a secondary, or low-side, current surge withstand design test be included in the IEEE test standards. It was charged with reviewing all information on low-side surges and determining if revisions of dielectric tests of distribution transformers are warranted. Although agreement on a standard test has not been reached, substantial work has been done and is summarized in this report. The report describes the problem of failures of distribution transformers due to low-side surge phenomena and how it is being addressed by the industry. The problem is described in historical perspective, along with the viewpoints of the task force members. The system and the transformer parameters that influence the problem are discussed. Proposed solutions and their trade-offs are presented