"Vacuum for HV applications - Perhaps not so new? - Thirty Years Service Experience of 132kV Vacuum Circuit breaker"

In 1968 four 132kV, 3500MVA vacuum circuit breakers were manufactured by AEI in the UK and commissioned into service by the then Central Electricity Generating Board in the UK. This paper describes the design and history of these revolutionary circuit breakers which are believed to be the first application in the world of vacuum circuit breaker technology for circuit breakers at transmission voltages. Although technically successful, in the 1960's these circuit breakers did not compare favourably against the SF6 circuit breakers which had been developed some years previously and were being introduced to replace oil and air for transmission voltages. As a result vacuum did not go on to dominate the HV circuit breaker market, as it did for the MV market. This was mainly due to limitations of the vacuum technology at the time, as a consequence of which the AEI circuit breakers used eight interrupters in series per phase. This resulted in a complex and expensive operating system, which was excessively costly in comparison with the oil and SF6 circuit breakers of the time