I need to replace an AH 10A 250 V glass type fuse and the closest I
have is an AGC 10A 32V fuse. They are the same physically, but are they
the same electrically? The actual fuse element inside the 32V fuse
looks thicker than the 250V fuse.
You can substitute a higher voltage rating for a lower one, but not the
"other way" around. The 250 volt rating means the fuse will safely open
a 250 volt circuit without "exploding" or developing an interal arc
which could maintain current flow longer than would be safe.
Others have already answered the question of using a lower
voltage-rated fuse in a higher voltage application as a definite no.
As far as the apparent visible size of the element from one fuse to
another, that's a design consideration related to the material
composition, fuse response time, etc. Since dissipated power is I^2 *
R, the current to melt the fusible link is dependent on R which is
obviously intimately related to the material, etc.
Zero crossings may be used by AC fuses to help extinguish the arc. Some
fuses are AC only, some have lower voltage ratings on DC.
Swithes have AC-DC limits also. Quiet switches we commonly use break the
circuit slowly and use the AC zero crossings to help extinguish the arc.
Quiet switches are probably all AC-only. DC requires a fast snap action.
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