Case Studies Involving Insulating Liquids and Materials from the Doble Materials Laboratories

Lance R. Lewand & Paul J. Griffin 
Doble Engineering Company


This paper discusses cases that involved problems with apparatus or insulating materials that have been detected and studied using oil tests to help determine the root cause.

Several of the cases involved dissolved gas analysis and detection of fault conditions. This includes problems that produced hydrogen besides partial discharge activity, ethylene to ethane ratios to better evaluate when paper in involved in localized high-temperature overheating problems, and testing for stray gas production.

One case is on oil quality and examines the formation of elemental (free) sulfur in oils that have stable corrosive sulfur compounds but have been exposed to very high temperatures.

Another case presented is on oil tests to evaluate the condition of an oil circuit breaker.

The final case is on OCB materials and how a compromised o-ring was shown to be improperly manufactured.