High-Power Laboratory Tests on High-Capacity High-Voltage Oil Circuit Breakers

Although for many years many high-capacity outdoor oeb's (oil circuit breakers) have given satisfactory service with only field tests to establish their interrupting rating, it is acknowledged that supplementiing laboratory tests are required to assess fully their ultimate capabilities. Laboratory tests can be made of any severity and the limitations of a given breaker design can be observed. This paper covers a test program utilizing the maximuin short-circuit output of one of the largest testing laboratories, to observe the performance of high-capacity interrupters for ocb's, with voltage ratings of 69, 115, 138, 161, and 230 kv. Previous field tests had given indications that the designs, in general, were satisfactory up to the limits tested. These additional tests were made for the purpose of finding out more about their interrtlpting characteristics and their ultimate limits. Two single-pole test units were used: one for the 69-kv tests, and one for the 115-to 230-kv tests. In recent years, there has been general agreement on the impracticability of separate interrupter designs for the many possible interrupting and voltage ratings. Therefore, in addition to the standardization of a small number of ratings by the industry, manufacturers have carried standardization a step further by utilizing fewer different interrupter designs. This point is applicable to the last-mentioned group of ratings where a single interrupter design was considered approxpriate for voltages of 115, 138, 161, and 230 kv.