AGING OF EQUIPMENT IN THE ELECTRIC UTILITIES

Multiple stress-induced aging occurs in all electrical equipment. However, the dominant mechanism of aging may differ for each class of equipment. Electrical insulation in equipment employed by the electric utilities. encompasses all types of polymers! glasses, elastomers and semicrystalline polymers. Both thermoset and thermoplastic materials are employed. The nature of the insulation is designed to meet a variety of needs, depending upon 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. This paper reviews the utility network system, types of equipment, types of insulations used, and property requirements of the electrical insulation. It describes the typical mechanism of aging for each class of utility equipment and analyzes the limits of any multifactor aging relationship's ability to predict a component's life.