Transformer leak repair story from Polywater®

The fast and effective repair of power transformer oil or SF6 leaks is an important part of a consistent power supply that minimises economic losses...


The fast and effective repair of power transformer oil or SF6 leaks is an important part of a consistent power supply that minimises economic losses for both power utilities and their customers. Ongoing transformer maintenance programs are critical to reliable electrical power generation and services. When immediate replacement of a transformer gasket is not feasible, a fast and reliable repair solution is required on location for a gasket oil leak.

The following Leak Repair Story from Polywater will describe a leak repair scenario often encountered in the field: The repair of a generating transformer bell tank gasket leak in India where Polywater® PowerPatch® Leak Repair system was used to repair oil leaks to maintain a reliable power supply.

 

Oil leakage problem to be resolved

An Indian generation utility was preparing for overhauling its transformer fleet during a scheduled annual shutdown. However, oil leakage from the Bell Tank of a 260 MVA generating transformer (GT) gasket and bolts was a serious concern for its owner.

 

Customer repair options

The transformer owner had two options available to fix the gasket leak: gasket replacement or gasket leak repair. The former is an intrusive option as the transformer oil must be removed and the bell tank needs to be lifted to replace the gasket. The latter option, gasket leak repair, is a non-intrusive process where the leak is repaired from the outside, eliminating the need for lifting and oil removal.

In this case, the GT had provided reliable service for over a decade, but the asset manager was hesitant to expose the core of the transformer to atmospheric oxygen and moisture if traditional gasket replacement practices were to be used. It was also determined that the costs of lifting the active part of the transformer and oil treatment required for the intrusive replacement option would be high. The customer also needed to minimize the risk of opening a well operating transformer to expose it to atmospheric moisture. The chosen option for the upcoming shut-down needed to be a sealant technology that allowed for the leak to be stopped without the need for oil treatment and need to lift the bell tank.

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