Fast-burn and slow-burn fuses

[Guest]

What is exactly the difference between fast-burn and slow-burn fuses?
How much faster is a fast-burn fuse?

[MYSTERY]

If you are refering to mains fuses:

fast blow - will blow if the current exceeds rated amount

slow blow - will not blow if it recieves mains spikes or surges

hope this helps

[Couch]

Only fast blow fuses should be used on electronics, they will protect your circuit against damaging over-currents. Slow blow fuses are primarily used in circuits that will require more current over a small period (like a motor, it needs more juice to start up) - these are not to be used on electronics, or you will smell the burning long before the fuse blows..

The time required to blow is dependant on the ratio of the current/rating - most fast acting fuses will take seconds to blow if at or slightly over their rating. The time to blow decreases exponentially as the over current ratio increases - at 5 times overcurrent, the time to blow is in the neighbourhood of 5ms.

If you require better protection than this you can look at circuit board fuses that are much more sensitive. Do some searches on Digikey or one of the other electronics parts sites, they are a great search tool for information and datasheets.

Thanks
Dave