Testing of vacuum circuit breakers: specific issues and developments

In the international standards for medium (and high-) voltage circuit-breakers no distinction is made in test requirements between circuit breakers with different arc-quenching media, like SF/sub 6/, oil and vacuum. This has led to the necessity to formulate a few additional test-requirements and interpretations that are specific to vacuum circuit breakers (VCB) only. In this contribution, the background and practical application of several procedures, now generally adopted in certifying test-laboratories is elucidated. In addition, results of a new high-resolution high-frequency current-zero measuring system are presented.