Insulation of HVDC transformers should be ______

A)
wet always
B)
dry always
C)
can be dry or wet
D)
None of the above

Correct Answer : Option (B) :   dry always


Explanation : Because of the effect of moisture on the resistivity of insulation material, it is necessary to obtain and maintain a high level of dryness in the insulation of HVDC transformers. This is equally important in service as it is in the factory at the time of testing.