A cost effective battery bank for I/sup 2/t testing and evaluation of electrical switchgear

The electrical design and mechanical construction of a 50-kA step-switched battery bank is described. Individual fuses protect each of the 40 parallel isolated strings of three series (12-V) batteries. Step current waveforms of 12.5 kA, 25 kA, 37.5 kA, and 50 kA are produced by eight sets of pneumatically driven 20-pole step switches and current-limiting stainless steel trombone resistors. Group 65 Motorcraft car batteries are used to give an I/sup 2/t capability of better than 5*10/sup 9/. The battery bank has well over 1500 shots, with testing of commercial switchgear continuing. In addition to the battery-bank engineering data, results of repetitive testing of vacuum interrupters at their I/sup 2/t limit will be provided.<>