Laminated plastics for switchgear

Todays growing distribution systems require economical protective devices with more and more interrupting ability. The current trend in oil circuit breakers is toward interruption of higher currents in a shorter period of time. Fast, efficient performance results in greatly reduced arcing times and the amount of the electrical energy dissipated. This in turn means reduced carbonization of oil and contact burning and better system coordination by providing faster short-circuit interruption. Auxiliary equipment such as air brake switches and open fuse cut-outs must also be capable of handling higher system loadings with full assurance of positive interruption in the complete range of fault currents. Epoxy glass tubing is being used to meet the above requirements and also as a protective liner in the large air blast circuit breakers to prevent a sudden release of gas or air in the event of external damage to the outer porcelain shell.