Circuit interrupters mediums

Theory of circuit interruption with different switching mediums (theory of deionization) 19/629... 

It is for the user to choose the most appropriate circuit breaker to suit requirements, application and cost. Here we discuss briefly the philosophy of circuit interruption and the effect of insulating and quenching mediums on the arc extinction of these breakers. We also deal briefly with the constructional features and application of such breakers. For more details one may refer to the manufacturers catalogues and literature available on the subject. 

Vacuum is finally judged to be the best medium to quench the arc plasma and interrupt a circuit undci the most adverse conditions. Figure 19,24 gives cross-sectional views of one pole of a vacuum circuit breaker and a typiciil construction of the arcing contacts and Figure... 

A search for other gases/mixtures for use in circuit breakers showed that while no other gaseous medium outperforms SFe in circuit breakers, some gases/mixtures can be considered. The performance ratings (based on the critical interruption current h for a given surge impedance Zq) relative to SFg of some such media are listed in Table III. 

A primary section provides for connection of incoming medium- or hi -voltage circuits, usually with disconnecting and circuit protective devices such as switches and circuit breakers. A transformer section includes one or more transformers. A secondary switchboard section provides for connection of secondary distribntion feeders, each with a circuit protective switching and interrupting device. 

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