using ac fuses in dc circuits

I have come across some cheap ac ceramic fuses 50 amp, 100 amp and wonder if is safe to use in one of my solar projects. Have a 12v

200ah battery and 1000w inverter. I heard as a rule of thumb you can use AC fuses at half the rating if used in DC...
Reply to
lentildude
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"lentildude"

** Half of WHICH rating ??

.... Phil

Reply to
Phil Allison

I just found this on the net, seems ok to use them in DC;

The difference between an applied AC voltage or is DC voltage to a fuse; The fuse-links are on principle suitable for use at alternating and direct voltage. The breaking capacity at direct-voltage is however considerably lower than the one at alternating voltage. The performance of the fuse-link at direct-voltage mainly depends on the size of the time-constant =3D L/R of the load circuit.

Glass body fuses seem to have a DC voltage rating half that of a maximum AC voltage rating [in general]. While Ceramic cases appear to have the same maximum voltage rating regardless of the operating voltage, AC or DC.

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Reply to
lentildude

"lentildude"

** Quit top posting - it is really DUMB !!

I just found this on the net, seems ok to use them in DC;

" The difference between an applied AC voltage or is DC voltage to a fuse; The fuse-links are on principle suitable for use at alternating and direct voltage. The breaking capacity at direct-voltage is however considerably lower than the one at alternating voltage. The performance of the fuse-link at direct-voltage mainly depends on the size of the time-constant = L/R of the load circuit.

Glass body fuses seem to have a DC voltage rating half that of a maximum AC voltage rating [in general]. While Ceramic cases appear to have the same maximum voltage rating regardless of the operating voltage, AC or DC.

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"

** Tells you almost nothing.

The fuse "rating" being talked about is the fuse's " maximum breaking capacity " in amps - the only way to know that is look up the maker's published data !!!

The number will vary with the actual circuit voltage and also depends on whether the voltage is AC or DC.

Mostly, makers just specify the breaking capacity as so many amps at 250 volts AC - usually the figure for 12 volts DC is the same.

Your problem is that you have no idea what breaking capacity is needed - cos it relates to the worst case scenario FAULT current and not the normal running current level.

..... Phil

Reply to
Phil Allison

I you don't understand the subject, don't rely on the net.

Graham

-- due to the hugely increased level of spam please make the obvious adjustment to my email address

Reply to
Eeyore

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