Evaluation of Seismic Qualification Procedures for High-Voltage Substation Equipment

The standard industry procedures for the seismic qualification of substation equipment were assessed by analysis and triaxial experimentation using the earthquake simulator at the Pacific Earthquake Engineering Research Center, which is headquartered at the University of California at Berkeley. Information on the qualification of in-service high-voltage transformer bushings is presented. Two of the three classes of bushings performed substantially better in the laboratory than in the field during modest earthquake shaking. The excellent performance of these two classes of bushings calls into question the standard industry procedures for equipment qualification. Improved procedures that account for equipment interaction, permit uniaxial qualification, better address response amplification due to transformer tank and turret flexibility, and utilize standardized earthquake histories and filtering procedures, are needed.