Fuse Marking

Indeed.

Just for the benefit of the OP, the prefix T means slow acting ( 'slo-blo' type ) as in T for time delay, although note that US and IEC fuse specs are quite different in detail. H suffix means high breaking capacity ( > 35A IIRC ) and may be in a ceramic package ( but not always ).

Graham

I want to replace some fuses marked F10AL250V

These are 10A, 250V rated fuses. But what does the L mean ? Possibly LAG as in time lag ?

thanks Roger

Roger, everything you might need to know about fuses. You can download The Fuse Bible from here

Magic. Thank-you both for your help.

Roger

do you know about rupture current ratings? that is the maximum fault current the fuse can interrupt (without arcing over and then blowing itself to smithereens). For glass fuses, its bugger all. HRC = High Rupture Current (80kA typ.). A new NZ house has a fault current of about

6kA, which explains how come techs find glass fuses all blown to shit. And why microwaves have ceramic fuses, which absorb the fault current by melting sand.

I had to use HRC fuses in a 48Vdc LED video screen I worked on. Each module drew 55W at 48Vdc, but there were 2,000 of them fed from the one telco PSU (100kW), which could happily drive 2kA into a dead short, continuously. So I needed a fuse with a 10kA *DC* interrupt rating (a lot harder than AC). I used a Bussman/Cooper ABC series 2A (10kA dc rupture) fast-acting fuse in each psu, and a MDA series 30A (10kA dc rupture) slow-acting fuse in each data/power distribution module (drives

12 psu's). why slow acting? couldnt get a fast 30A fuse with 10kA dc interrupt rating. And the pcb silk-screen has "2A/10kA" written underneath the fuse, in big letters.

Cheers Terry