CIRCUIT-BREAKER ARC TEST FACILITY.

This paper describes some of the test facilities available at the University of Sydney for the study of circuit breaker arcs, and summarizes recent progress. The techniques described are being applied to experimental gas-blast interruptors with several aims in mind. The first aim is to improve understanding of the behavior of this type of arc. The results of laser schlieren photography show very clearly that the plasma core of these arcs has an influence which extends to much larger distances than the extent of the strongly visible region and that this, in turn, has a major bearing on the final recovery of dielectric strength following current zero. A second aim has been to build on this understanding to pinpoint specific tests which may be useful on full-scale circuit breakers to give an adequate proof of performance for a wide variety of power-system duties. The ability to make sensitive post-zero current measurements should make it possible to do more than judge performance in terms of a ″go″ or ″no go″ result. Such tests will give a good indication of how close a breaker is to its interruption limit, and in this way improve both the economy of, and information obtained from high-power tests.