MIDWEST recently sold a 2500 amp 15 Kv old used air circuit breaker for $5000.00. It was in excellent condition and years ago it would have sold for $25,000.00. One might think the reason for the big drop in price is because of the age. But the biggest reason is the use of vacuum technology in 15 Kv class circuit breakers. Vacuum breakers are used to replace air circuit breakers in new 15 Kv switchgear. And many old medium voltage air circuit breakers have been replaced with new vacuum breakers or retrofitted with vacuum technology.
Maintaining and Testing 5 Kv and 15 Kv vacuum circuit breakers is a lot easier than the old air circuit breakers. And the vacuum breakers are a lot easier to handle. An old or obsolete air circuit breaker could weigh 1500 pounds. The new vacuum equipment is half that. The biggest difference is the simple replacement of the old heavy arc chutes with the simple vacuum bottles. For an historical perspective, the early 1900s saw the use of big old oil circuit breakers. The mid 1900s began the use of air circuit breakers. And the late 1900s began the use of vacuum breakers. MIDWEST has worked on all of them and the vacuum breakers are just so much simpler to service. Some older electricians and switchgear service technicians do not trust the vacuum circuit breakers as a safe circuit open device. I wouldn’t trust vacuum circuit breakers or old air circuit breakers or obsolete oil circuit breakers as open circuit protection. The circuit breaker must be racked out and, of course, the circuit grounded before any circuit work or equipment maintenance. By racking the breaker out, one has a “visible open.” Medium voltage air circuit breakers are an example of equipment becoming obsolete long before they actually wear out, all due to new technology.