When to Replace Aging Transformers, Part 2: Guidelines to Replace Older Transformers Before Failure

Abstract

Part 2 of “when to replace aging transformers” uses the initial case study to define basic problems surrounding transformers that were in service for more than 60 years. This article provides an update on transformers returned to service and that are now 71 years old. It expounds more deeply on the insulation system, testing, and criteria used to determine whether to allow a transformer to remain in service or to be replaced. It explores the technique of using the degree of polymerization (DP) to assess the remaining life of insulation as defined in the standards. With today’s information gathering techniques and database manipulation, the method of online monitoring will be discussed. Additional information is available in the paper “When to Replace Aging Transformers” [3].