Much of the power system equipment in use today is nearing or has passed its predicted operating life, and we are pushing equipment to increasingly higher levels to meet demands. Injuries, failed equipment, unscheduled downtime, and loss of production are concerns that require knowledge of in-service power system apparatus. This is coupled with the competitiveness of the electrical energy market. The prevention of faults and defects in substation primary equipment is considered a major differentiating factor in the quality of power delivered by utilities. The reduction of faults and defects that cause interruptions in the supply of electrical energy significantly improves service performance rates.