Interrupting capacity tests on circuit breakers

IMPROVEMENTS in circuit breakers have been accelerated by the availability of short-circuit testing laboratories. Some of these laboratories are of sufficient capacity to test circuit breakers of reasonably high interrupting ratings at their full rated current and voltage. No laboratory, however, has sufficient capacity to make such tests on the largest circuit breakers now used. It has therefore been necessary to study the fundamentals of circuit interruption within the limits of laboratory equipment. Also, much study has been given to the determination of the differences between field service and testing conditions.