Editing Fuse (electrical) (section)

===Time vs current characteristics===
The speed at which a fuse blows depends on how much current flows through it and the material of which the fuse is made. Manufacturers can provide a plot of current vs time, often plotted on logarithmic scales, to characterize the device and to allow comparison with the characteristics of protective devices upstream and downstream of the fuse.

The operating time is not a fixed interval but decreases as the current increases. Fuses are designed to have particular characteristics of operating time compared to current. A standard fuse may require twice its rated current to open in one second, a fast-blow fuse may require twice its rated current to blow in 0.1 seconds, and a slow-blow fuse may require twice its rated current for tens of seconds to blow.

Fuse selection depends on the load's characteristics. Semiconductor devices may use a fast or ''ultrafast'' fuse as semiconductor devices heat rapidly when excess current flows. The fastest blowing fuses are designed for the most sensitive electrical equipment, where even a short exposure to an overload current could be damaging. Normal fast-blow fuses are the most general purpose fuses. A ''time-delay fuse'' (also known as an ''anti-surge'' or ''slow-blow'' fuse) is designed to allow a current which is above the rated value of the fuse to flow for a short period of time without the fuse blowing. These types of fuse are used on equipment such as motors, which can draw larger than normal currents for up to several seconds while coming up to speed.