Behaviour of contactors protected by fuses during short-circuit currents

The behaviour of contactors protected by fuses under short-circuit currents is analysed using a simple model to represent the electric circuit and the contactor. The resulting performance equations are given and an example of application is illustrated. Experimental results are reported which agree well with those computed. The existence is confirmed of a definite range of prospective short-circuit currents in which the protective action of the fuse lets through the most severe stress experienced by the contactor.