Question

An on load tap changer is installed on a transformer and shares the transformer tank. The tap changer mechanism and contacts and the transformer windings are in the same oil volume. Due to mechanical wear and contact oxidisation, one tap changer contact begins to get hot ( a few hundred degrees). This fault persists for months and will eventually cause the failure of the insulation on adjacent components. What protection systems or inspection procedures might detect this developing fault?

Select one:

a. All of the above

b. Frequency response analysis (FRA)

c. Dissolved gas analysis (DGA) or a Buchholz relay if gas is being produced

d. Magnetising Current Harmonics

Answer 1

The answer is C.

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