Vacuum Interrupter Testing

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Predicting remainder of field life finally becomes easier

BY FINLEY LEDBETTER, Group CBS

Vacuum interrupters (VIs) have widely replaced older air-magnetic and oil interrupters for circuit breakers rated at one kilovolt (kV) or higher. These devices offer up to 10 times the expected lifetime than newer SF6 (sulfur hexafluoride) gas interrupters.

Unfortunately, nothing lasts forever. Manufacturers predict that most of their interrupters have a service life of 20 years; however, users generally ignore this fact. Consequently, this negligence has placed a large portion of North American industrial and utility distribution switchgear at risk of failure.

For the most part, users can prevent failure through diligent testing. Furthermore, no one suggests that ignoring possible failure is acceptable. Every vacuum interrupter will fail; we just do not know when. Luckily, there are several traditional methods and one new field-testing method for verifying the isolation capability of your VI-protected circuit breakers and motor controls. Electrical Source Magazine will cover these capabilities in this issue’s Testing and Maintenance Channel.

Read the full article in our digital magazine

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