Slow Blow or Fast Blow fuse?

[ricko_uk]

Hi,
with reference to the attached schematic, would you recommend a slow blow or fast blow?

I was thinking that when initially the circuit receives power C14 and C15 are discharged and there might be a (relatively) large current surge. So a slow blow fuse might be better?

But then again the current surge might be too short to need a slow blow?

Or maybe I should think in a different way when coming to choose the type?

Thank you

[Benta]

Doesn't matter. You'll never have more than 13 mA running through it.

[ricko_uk]

Thank you Benta,

I got that schematic from a reference design. The fuse is set to 1A, I assume in case any components downstream fail. What do you mean never have more than 13A?

Do you mean because R11 and R12 would limit the current? I thought the fuse is there perhaps in case R11 and R12 short?

Sorry but not much experience in mains design and requirements.

Thank you

[james_s]

13 *milliamps*, that's 0.013 amps. You've got 30k worth of resistors in series which will limit the maximum current according to Ohms law. I would consider just using flameproof resistors and skipping the fuse.

[Benta]

The fuse is good practice (and depending on your electric code rules) for fire protection. It's not there to save your circuit.

[james_s]

They make flameproof resistors that are designed to function as a fuse, sometimes they're called fusible resistors. They're quite common in low power applications like that.