Circuit Breaker Sales & Repair is proud to be among the first to offer Magnetron Atmospheric Condition (MAC) testing services to its customers for determining the remaining life of vacuum interrupters used in medium-voltage circuit breakers and contactors. Before MAC testing, technicians only could determine if a vacuum interrupter passed or failed using a HiPot test.
Vacuum Interrupter Testing Service
Using a MAC-TS4 vacuum interrupter test set, our technicians can easily determine the pressure inside a vacuum interrupter; and, along with wear and number of operations, predict the usable life of the vacuum interrupters used in your circuit breakers and contactors. Until now, this type of testing could only be done at the assembly plant.
Don't guess about the health of your vacuum interrupters. Contact us to discuss your application or arrange for testing of your vacuum interrupters.
How HiPot Tests Can Make Bad Vacuum Interrupters Appear Good
If the internal pressure of a vacuum interrupter is just past the point of failing a HiPot test, a phenomenon can occur that can temporarily reduce the pressure inside enough to pass the test.
Applying a high voltage breaks down, or ionizes, the gas molecules inside the vacuum interrupter into charged particles, ions, and electrons. After the high voltage is removed, these charged particles immediately begin recombining into gas molecules. under certain conditions, some of these charged particles may "stick" to the inner surfaces of the vacuum interrupter which, in turn, reduces the number of gas molecules inside.
When the number of gas molecules is reduced, the pressure is also reduced. This reduction in pressure is temporary and dependent on a number of factors; however, it can result in a vacuum interrupter's internal pressure being reduced enough to pass a HiPot test. These remaining charged particles eventually will recombine and return the pressure to an unsatisfactory level. After this recombination occurs, the vacuum interrupter will, again, not pass a HiPot test.