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
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
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.