[en] The report covers seismic testing performed on the Engineered Safeguards Test Cabinet, Nuclear Instrumentation System Instrument Bus Solatron Line Voltage Regulator, and two models of Vital Instrument Bus Inverters over the range of 1 Hz to 35 Hz. To demonstrate its ability to perform under earthquake disturbances, the above equipment was subjected to vibration tests which simulated the seismic conditions for the high seismic class of plants. During testing, the equipment was operated and critical functions monitored to verify their proper performance. The results show that there were no electrical irregularities that would leave the plant in an unsafe condition. Tests were conducted on the Engineered Safeguards Test Cabinet in November of 1972, at the Acton Environmental Testing Corp., Acton, Massachusetts, and on the Nuclear Instrumentation System Instrument Bus Solatron Line Voltage Regulator and Vital Instrument Bus Inverters during July and August 1973, at the Westinghouse Astronuclear Laboratory, Large, Pennsylvania