The Principle Of Coordination Between The Melting Time Of The Drop-out Fuse And The Upper Circuit Breaker

The melting time of the drop out fuse fuse should be coordinated in a stepped manner with the protection curve of the upper circuit breaker to ensure that the fuse takes priority in short circuit and that the upper circuit breaker has room to operate in overload or minor faults. When selecting the fuse, the time-current characteristic (TCC) of the fuse should be used as the basis to select the appropriate rated current and fuse band to ensure that the melting time is less than the upper protection setting and that there is at least one level difference between adjacent fuses to achieve selectivity.