Line Insulation Design for APS 500-ky System

An attempt has been made to obtain an optimum insulation system which fulfills all APS requirements. The three primary areas which dictate insulation design limits are normal frequency voltages and contamination, switching surges, and lightning. Contamination limits were established by an extrapolation of operating experience at other voltage levels. The switching surge limits were established by miniature system studies coupled with experience gained in laboratory and field tests. The lightning performance was calculated using accepted methods and optimum improvement was obtained by using an incremental cost method to evaluate the cost of improved grounding, increased numbers of insulators, and better shielding angles. The respective design limits were coordinated into a final design.