Non-invasive Evaluation of Internal Pressure in Vacuum Circuit Breakers

Since the switching operation of vacuum circuit breakers affects the status of the contacts surface as well as the amount of free particles remaining in the interrupting chamber, the internal pressure of vacuum interrupters (VIs) is also influenced by the process of interruption of the current. With each switching operation by the vacuum circuit breaker (VCB), the existing dielectric losses a percentage of the absolute vacuum. With the internal pressure changes of the VIs, all of its features change and the VCB operation is malfunctioning. This paper establishes a relationship between the two parameters of contact erosion and the internal pressure of the vacuum. By providing a simple algorithm, the feasibility of online monitoring of two parameters has been discussed.