Aging of equipment in the electric utilities

The authors point out that multiple-stress-induced aging occurs in all electrical equipment. However, the dominant aging mechanism may differ for each class of equipment. Electrical insulation in equipment employed by the electric utilities encompasses all types of polymers. Both thermoset and thermoplastic materials are employed. The nature of the insulation is designed to meet a variety of needs, depending on the equipment environment. For example, transformer insulation requires thermal resistance at moderate operating stresses, capacitors operate at high electrical stresses and without excessive thermal load, and cables require only moderate thermal resistance and operate at relatively low voltage stress. The utility network system, types of equipment, types of insulation used, and properties required of the electrical insulation are reviewed. The typical aging mechanism for each class of utility equipment is described, and the limits of any multifactor aging relationship's ability to predict a component's life are analyzed. >