Insulating Oil Testing
Transformer oil reacts with oxygen to form organic acids, esters, and phenolic
compounds which ultimately leads to sludging of the transformer. The rate of
this phenomena increases with an increased exposure to air and temperature.
Also it should be noted that oxygen is more soluble in oil than found in air. Not
only will the sludge adversely affect the dielectric properties of the oil, but it
will also interfere with dissipation of heat within the transformer. The purpose
of these tests are to chart the gradual deterioration and take preventative
measures before insulating oil reaches a point where failure of the transformer
is inevitable. The routine tests and sampling procedures that are conducted on
insulating oil are shown in Table 4.2, and are discussed in text of this chapter