Fusing practices on distribution systems

E. G. Newton (General Electric Company, Pittsfield, Mass.): The data on the fusing practices on distribution systems as compiled and presented by Parsons and Wallace give a good over-all picture of existing practices and problems. However, in discussing the weighted average fusing ratios of their Figure 3 they state, “The ratio of the minimum melting point of the fuse link to the full-load current of the transformer will be twice that shown in the figure, as all these data are based on N-rated links.” Then they compare the earlier data shown by the dotted lines of the figure with the solid-line data which the authors indicate they corrected on the basis of the foregoing statement. This leads to their conclusion that “One factor probably contributing to the increased fusing ratio is the change in method of rating fuse links. This automatically would increase the fusing ratio if the use of the same link ratings were continued.”