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CAN I USE AN AC RATED FUSE IN A DC APPLICATION?

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CAN I USE AN AC RATED FUSE IN A DC APPLICATION?

Direct currents are very difficult to stop or interrupt when compared to

alternating currents. Alternating current sources reverse the flow of current

many times a second (in some locations 100 times a second on 50 Hz

systems). Each time the current reverses, it goes to zero in magnitude.

A zero current is very easy for a melting fuse to stop or interrupt—it is

already stopped, and there is no force trying to sustain an arc across the

fuse element.

DC currents, as the name implies, are currents that travel in one direction

only. They do not reverse. Fuses bear the entire burden (with no help from

the current) of acting to stop these currents. The internal elements of a fuse

must react to an over-current condition (usually by melting) and as they

react, they must do so with enough capability to interrupt the current from

flowing while extinguishing any arc that might form. DC fuses are relatively

sophisticated devices that have many different internal elements that must

work together.

There are fuses with equal AC and DC voltage ratings but in most cases,

the DC voltage rating is significantly less than the AC voltage rating. If a

fuse only has an AC voltage rating, it most probably was not designed for

DC applications and hence has never been tested within a DC environment.

If you would like to ask if a specific AC rated fuse can be used in a DC

environment, please contact Aidun Electric.