According to standard electrical maintenance schedules, thorough cleaning of a power transformer and checking for oil leakage at joints is typically performed on which basis?

Dampness in electrical winding can be removed by drying out the equipment thoroughly in a hot chamber or in an impregnating plant. What should be the ideal inside temperature of the chamber?

If an electric fan runs with an abnormal buzzing sound, it is most likely due to a defect in the _______.