A New Three Phase Synthetic Test Circuit for HVAC Breakers of High Interrupting Power - As Applied to a New 242kV SF6 Single Tank Breaker

For short circuit tests with a new 242kV/4OkA single tank breaker, (i.e. all three poles in one enclosure) an improved three phase synthetic test circuit has been developed since the required direct testing power is generally not available even in the largest laboratories. The circuit enables three phase testing at rated voltages of at least 242kV (and higher) and also facilitates 3-ph testing in smaller high power stations. Successful tests with a single tank 242kV CB demonstrate the applicability of the circuit. The problems of three phase testing are first discussed in general, whereafter a new test procedure is proposed based on the physical particularities of HVAC circuit breakers, as an alternative to common testing practice.