So far we have not broached the subject of voltage rating of a fuse. However, even a fuse has a maximum rated voltage. It is the highest voltage at which fuse is designed to operate and it is important that a fuse should not be asked to interrupt current above this voltage. Faults can be line to ground or line to line. When applied phase to ground on three phase systems, the voltage rating of the fuse should equal or exceed the phase to ground system voltage. When applied in the line on the same system, the conservative approach is to choose the fuse voltage to be equal to system phase to phase voltage. Sometimes, for a fuse both maximum and minimum interrupting currents are specified.
|
