ABSTRACT
Prior to 1970, little guidance existed for the seismic design of electric substation equipment. Even in earthquake-prone regions, typical design practices consisted of applying low static lateral force coe¯- cients modeled a¢er building codes for the seismic design of high-voltage equipment and their supports. It was common for utilities to each develop its own set of seismic quali™cation requirements, which varied from one another depending on experience, site-speci™c hazards, engineering practices, and other considerations. In the 1970s through 1990s, several large-magnitude earthquakes struck California, causing millions of dollars in damage to substation components (see Figures 13.1 through 13.4), consequent losses of revenue, and disruption of service for a large number of customers. High-voltage equipment was o¢en damaged due to the use of massive and brittle porcelain components and the absence of recognized seismic design standards and technical guidance. As a result of these losses and the increasing importance of reliable electric service, it became apparent to owners and operators of substation facilities in seismically active areas that the existing seismic design practices for substation components were inadequate.
