Vacuum circuit breaker with contact wear indicator tool

A circuit breaker with an erosion gauge tool comprising:

• a sealed vacuum chamber;
• a first stationary contact sealed within the vacuum chamber;
• a first electrical conductor connected to the first stationary contact at one end, sealably penetrating the vacuum chamber and terminating at the other end in a first electrical connector;
• a moveable contact sealed within the vacuum chamber and moveable between a first position, out of electrical communication with the first stationary contact, and a second position, in electrical communication with the stationary contact;
• a second electrical conductor in electrical communication with the moveable contact at one end and terminating at the other end in a second electrical connector;
• means for moving the moveable contact between the first and second positions in response to an actuation command;
• a stem coupling said means for moving the movable contact to said movable contact;
• a drive insulator coupled to said stem, said drive, insulator having at least one disk;
• a first feature identified on said stem or drive insulator;
• a second feature identified on said circuit breaker;
• an erosion gauge tool having a body having a fixed dimension establishing spacing between said first locator feature and said second locator feature at a maximum allowable erosion of said contacts.

A method of measuring the erosion of the movable contact in a circuit breaker having a stationary contact and movable contact, movable between an open position and a closed position, both of which are sealed in a vacuum chamber housing, said movable contact being coupled to a stem and a drive insulator, said method comprising the following steps:

• a) identifying a first locator feature on said stem and/or drive insulator;
• b) identifying a stationary second locator feature on said circuit breaker below said first feature;
• c) operating said circuit breaker for a period of time;
• d) providing an erosion gauge tool having a means for comparing the distance between said first and said second locator features;
• f) comparing the location of said first and second locator features;
• g) replacing at least one said contact if said first and second locator features are beyond a predetermined distance.