Using fuses to protect a device based on semiconductors may make
you feel good, but it will seldom accomplish what is intended.
The reaction time of fuses is just too slow to actually protect
the semiconductors in most cases. When there is an overload
rather than an outright short, and the semiconductors were
designed with sufficient margin, it can work; but more often the
event that we are trying to protect against is indeed a short
circuit and the semiconductor is killed before the fuse has time
to react. For this reason, many systems that have semiconductors
are designed with fast reacting internal electronic circuits to
protect them against short circuits. The G203V stepper motor
driver and the G540 driver box are examples of this approach.
This does not mean that there is no need for fuses. They can
help by preventing total melt down or flame out even if they do
not save the semiconductors. This makes it more likely that the
unit will be repairable by replacing the semiconductors. Fuses
also serve to pro