Mill experience estimating vacuum interrupter service life using MAC testing - phase II

A previously-presented PPIC paper reported the results of use of alternate testing technology employing a magnetron device to apply a magnetic field, external to the VI (vacuum interrupter), to enable estimation of vacuum integrity. This process is known as MAC (magnetron atmosphere condition) testing. Results were reported from one mill outage in 2013, encompassing approximately 50 VI's. The data collected was presented along with suggestions for integration of the MAC testing technology into existing circuit breaker PM efforts. This paper revisits vacuum circuit breaker PM at that mill on the next major outage in 2015. Results are presented along with observations about the effectiveness of changes in the testing procedure. The mill's course of action in response to the second round of test results is detailed in this paper.