Empirical model of a current-limiting fuse using EMTP

An empirical model is discussed for research on current-limiting (CL) fuses used in distribution system applications. The main characteristic of a CL fuse is that it develops a voltage at its terminals which reduces the amount of energy generated in the protected equipment during a fault. The various stages of fuse operation are modeled using electric components. The model is of limited use, but its simplicity enables a nonexpert to use it without spending months to learn and program a sophisticated model. The model makes it possible to establish which closing angle of source voltage will produce the greatest of I/sup 2/t, assuming a melting time shorter than a quarter of a cycle. The model can also show how the let-through value of I/sup 2/t will be influenced by the voltage versus time profile of the fuse voltage. The electromagnetic transient program, EMTP, proved a useful tool for this development.<
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