Just blown a fuse....

[Steevo]

One to rival @Cab-over Pete's "I don't understand electrics"....

230v system, protected by a 2A fuse to run a control board and motor for a gate plus some 24v outputs for aux systems.

Just added a couple of other items to the 24v outputs that were previously running on a separate 12v 1A power supply. These are designed to run on 12v/24v system and would draw approx 2A each when supplied with 12v.

As soon as I connected these, the 230V 2A fuse blew. Before I jump straight in and replace the fuse (for it to no doubt blow again!) I thought I'd just run it past some wiser men than me.

250v 2A fuse will take a total of 500w, is that correct?
Adding the two 24v units drawing 2A at 12v would draw less at the supplied 24v?

Assuming 2A at 24v however, surely this was only adding a further 50w or so to the system?

The motor wasn't running at the time the fuse blew which makes me wonder if it's something more than an overload given I've added 50w to a 500w capacity system, the bulk of which would be drawn by the motor itself...which wasn't running at the time.

Am I making sense...or just confusing myself?

 

[Cab-over Pete]

Ah, you see, now I know EXACTLY what to do in your situation.













Call a sparky.

 

[Steevo]

Where's the fun in that....!?!

 

[Pheasant Surprise]

What were the extra loads you hooked up?

If they were simple resistive loads, then their current draw could go up with the system voltage. So double the voltage applied, double the current.

 

[farmerste]

take the fuse out and replace with a nail...........problem solved

 

[JJT]

 

[Milk maker]

Can't see the extra load being the problem must be a fault in your new 24 v circuit disconnect try one in at a time. Are they all AC or 24 v DC

 

[Mursal]

You just missed something ........

Do not replace the fuse with one of a larger value.
Disconnect the new circuit to make sure that's causing the fuse to pop?
If so power it off a battery (if DC) or the previous power supply watching to see if its own fuse (give it one) blows?

 

[Mursal]

I'm guessing the 2A fuse (if its on the 220V line) is there to protect the step down transformer/regulator (from 220 to 24V) so the new load just crossed the safe limit?

 

[Steevo]

You just missed something ........

Do not replace the fuse with one of a larger value.
Disconnect the new circuit to make sure that's causing the fuse to pop?
If so power it off a battery (if DC) or the previous power supply watching to see if its own fuse (give it one) blows?

There’s no way i’d up the fuse...it’s there for a reason and I’m lucky it blew not something expensive!

Thanks, will do. There is a backup battery I could possibly rig it up to that’s always on charge for the inevitable. I might be better to run it off that rather than the output on the board.

 

[TechWise]

Any pictures of the board? Transformers in these sorts of power supplies generally have a rating stamped on them in either VA or Amps. Are your 24V loads supplied at 24Vac or is there a AC-DC converter after the transformer? If there's a converter or regulator after the transformer, I'd be thinking transformer fault as the converter should not allow a downstream fault to overload the transformer.