The Importance of Through Fault Monitoring for Power Transformers

One of the more common causes of mechanical failure in power transformers comes from exposure to through faults. Most of today’s transformer protective relay systems provide comprehensive monitoring of these potentially damaging events but are rarely activated. In this paper we will define the characteristics of a through-fault, investigate various proper settings for a through-fault monitor, and present an actual case study of a severely damaged transformer exposed to this condition. We will also see examples of detecting mechanical failure in the transformer as it relates to a through-fault condition.