Fuse

A Fuse (electrical) is a piece of wire in a casingl characteristics. If too much current flows, the wire becomes hot and melts. This effectively disconnects the power supply from its load, and the equipment stops working until the problem that caused the overload is identified and the fuse is replaced.

There are various types of fuses used in power supplies.
 * fast blow fuses cut the power as quick as they can
 * slow blow fuses tolerate more short term overload
 * wire link fuses are just an open piece of wire, and have poorer overload characteristics than glass and ceramic fuses

Some power supplies use a very thin wire link soldered in place as a fuse.