Lord Consulting
Power Industry Asset Management Consultants
Lord Consulting
Power Industry Asset Management Consultants
Home » Technical Papers » Impact of Oil Properties and Characteristics on Transformer Reliability
Many maintenance guides still consider the insulating fluid to be a separate
component that can be
monitored and treated separately from the fluid-paper insulation system
or from the transformer as a
whole. In fact, the fluid is an integral part of the transformer playing
a dynamic role in the condition
of the entire system. Dielectric withstands strength of the oil and the
level of oil contamination
determines the dielectric safety margin of both new and service aged transformer
insulation systems.
In recent years there have occurred a number of failures
of transformers and shunt reactors,
connected to copper sulphide (Cu2S) formation. Reactive sulphur was originated
basically from noninhibited
oil containing presumably non-corrosive sulphur components as natural inhibitors.
Unexpectedly Sulphur appeared to be a dramatic source of conductive contaminants
badly affecting
winding insulation.
Another recent studies have confirmed that oil by-products
dramatically accelerate cellulose
decomposition and can be a decisive reliability-based factor in aged transformer
fleet2.
These phenomena make a good reason to reconsider role of fluid in
reliability aspects of power
transformers especially considering increased thermal and electric stresses
in modern equipment.
This paper is an attempt to summarize the problems
associated with impact of oil properties on
transformer reliability on the basis of service experience and lab’s
studies.