The Development of Vacuum Interrupter Conditioning: Keeping Interrupters in Service for 100+ Years

Group CBS has been working for years to develop a process that conditions and extends the life of vacuum interrupters by removing unwanted gas molecules from within the canister. The process has been proven in the lab and in the field. We are now able to extend the service life of vacuum interrupters by keeping the internal pressures within an acceptable range for an extended period of time. Our goal is to keep vacuum interrupters in service for more than 100 years.

The contributing factors are outgassing, small gas molecules that can penetrate seals, and events that create gas within the interrupter. Such events include an excessively high number of power interruptions and repetitive use. The basic science involves taking free unstable gas molecules inside the canister and accelerating them. They are accelerated to the point that when they strike certain materials within the canister, they convert from a gas to an oxide – a “solid” in effect. This reduces the number of free gas molecules within the interrupter, thus reducing the pressure within the interrupter.

This process is not suitable for every interrupter. Some may have excessively high pressures or may have seen so many operations that they are mechanically damaged. These interrupters are outside the limits of attaining meaningful improvements through the conditioning process.

To date, we’ve developed conditioning sets that include pressure sensing and ion current sensing circuitry. This is the integrated sensing technology that’s used to determine the actual pressures and to gather lab data. Through case studies, we are gathering enough data to feel comfortable that we can adequately reduce the pressures inside midrange interrupters by more than one order of magnitude. We can now do this with a simple 30-minute conditioning process, which we can perform either in the field or in the shop – most times without removing the interrupter from the circuit breaker or contactor.

Finley Ledbetter, Chief Scientist of GroupCBS, will be presenting current research on vacuum interrupter conditioning at the 2021 NETA PowerTest Conference, which is being held virtually March 8th – 11th. Join us at PowerTest, https://www.powertest.org/home

Previous research on this topic can be found at the Vacuum Interrupters Inc., website:  https://www.vacuuminterrupters.com/downloads/Reconditioning-of-Vacuum-Interrupters_presented-at-2019NETA-PowerTEST-Conference.pdf