Fast Blow Fuse Vs Slow Blow Fuse

In general the time required for a fuse to blow can be given i2t where i is the current and t is the time.

Fast blow fuse vs slow blow fuse.

How slow is slow enough. Slow blow fuse that can withstand a heavy current up to ten times its rated value for a small period of time before it opens. By using a slow blow fuse you bypass this problem because as mentioned before. 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.

For example assume a nominal load of 15 amps and an ambient. Slow blow fuse requires much higher time than the fast acting one. Read the manufacturer s label if it says fast or slow the fuse type is as it is labeled. Normally used for inductive loads like fans transformers etc.

Hence the fuses could be blown. Fast acting fuses should be used in motor circuits will blow more frequently. A slow blow fuse requires higher i2t than fast blow fuses to blow up. Selecting a fast blow fuse is fairly straightforward.

The uses for a slow blow fuse and a fast blow fuse. Start by choosing a fuse rated to carry about 33 percent more than the expected load i e the normal current should be 75 percent of the expected load current then adjust for ambient temperature. If it says f it means the fuse is a fast blow and if it says t or s it means it is a slow blow.