Patent 3991292 Issued on November 9, 1976. Estimated Expiration Date: November 9, 1993. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
A fluid-blast circuit interrupter of the puffer type is provided having two pistons connected in tandem to compress arc-extinguishing fluid in two separate volumes and to produce two separate fluid blasts. Valve action is provided to delay the initiation of the second blast until the interrupter contacts have reached the desired separation distance. By changing component dimensions the degree of compression of arc-extinguishing fluid may be changed without delaying the instant of contact separation.