A three-phase 34.5-kV feeder supplying a 4-MVA load is protected by 80E power fuses in each phase, in series with a recloser. The time-current characteristic of the 80E fuse is shown in Figure.
Analysis yields maximum and minimum fault currents of 1000 and 500 A, respectively.
(a) To have the recloser clear the fault, find the maximum clearing time necessary for recloser operation.
(b) To have the fuses clear the fault, find the minimum recloser clearing time. Assume that the recloser operating time is independent of fault current magnitude.
