Fast Blow Fuse Time

A slow blow fuse is normally used in the motor industry because when you start an engine at that moment a high current of electricity is passed through the electronic circuit.

Fast blow fuse time.

But not all surges are the same and not all time delay fuses are the same. In general the time required for a fuse to blow can be given i2t where i is the current and t is the time. A slow blow fuse requires higher i2t than fast blow fuses to blow up. For example if you send 40 amp current through a 30 amp fast blow fuse it will blow almost immediately.

The question is how to match the fuse to the load. Many people think that time delay fuses are less effective because they allow current overloads pass through the circuits. 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. Examples if a circuit has a current rating of 15 amperes and a voltage rating of 120 volts then the current rating should not exceed 15 amperes and the voltage rating should be at least 120 volts.

It would seem obvious that a fast blow fuse would be appropriate for a load without a startup surge and a slow blow or time delay fuse for the one with the surge. Fast acting fuses should be used in motor circuits will blow more frequently. But a slow blow one will melt its fuse wire after a specific period within 10 or 15 seconds. Slow blow fuse requires much higher time than the fast acting one.

The uses for a slow blow fuse and a fast blow fuse. These types of fuse are used on equipment such as motors which can draw larger than.