Wich fuse are you talking about.. The mains input fuse or the fuse on the output. what will you bee using the psu to power. what current does that draw.
Regards ian
Regards ian
5VA mains fuse.
Try to find the lowest T rated mains fuses available. Try T100mA or T250mA.
1A secondary fuse. Don't. It needs to be so large to survive the first charge from cold of the smoothing capacitors that it offers virtually no safety purpose.
Instead fuse after the smoothing capacitors and rate the fuse to suit the worst case "normal operating condition". Not the 1Aac rating of the transformer.
Try to find the lowest T rated mains fuses available. Try T100mA or T250mA.
1A secondary fuse. Don't. It needs to be so large to survive the first charge from cold of the smoothing capacitors that it offers virtually no safety purpose.
Instead fuse after the smoothing capacitors and rate the fuse to suit the worst case "normal operating condition". Not the 1Aac rating of the transformer.
Yes, T100mA mains fuse on a 220/240Vac mains system can supply ~23W continuously.
It will supply transient power of <=46W for many seconds and perhaps more than half a minute.
It will also supply short term transient power of 230W for a few milli-seconds, maybe even tens of milli-seconds.
A T250mA will take significantly longer to blow in event of a serious overload.
It will supply transient power of <=46W for many seconds and perhaps more than half a minute.
It will also supply short term transient power of 230W for a few milli-seconds, maybe even tens of milli-seconds.
A T250mA will take significantly longer to blow in event of a serious overload.
Of course it also depends on what is connected to the secondaries of the transformer. Not so true for your low power application but certainly true as the transformers and their loads get bigger and more capacitive.
If the load is highly capacitive the instantaneous current might be much higher. If the 100 mA fuse blows try a Time Lag Fuse. This is more prevelant with Toroidal Transformers.
If the load is highly capacitive the instantaneous current might be much higher. If the 100 mA fuse blows try a Time Lag Fuse. This is more prevelant with Toroidal Transformers.
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So if I know the power consumption in W of a device I can calculate the mains fuse, in my case that I only know I & V : 1A x 5V = 5VA...
The power fuse, ie the load fuse is normally 3 x the usual maximum load.
So in the 5V line, if you are expecting to use 1A constantly I would use a 3A or 3.5A fuse.
What we have been discussing is the Mains Fuse. This would need to be about 100mA and possibly Time Lag.
amps = VA / Mains voltage (formula to calculate mains fuse????)
5V x 1A = 5VA
5VA / 230 VAC = 0.021A (fuse value calculated wrong???)
It's to supply an E-MU 0404?
Tx used is a R-Core with dual secondary 9V wired in parallel for 30VA.
5V x 1A = 5VA
5VA / 230 VAC = 0.021A (fuse value calculated wrong???)
It's to supply an E-MU 0404?
Tx used is a R-Core with dual secondary 9V wired in parallel for 30VA.
So you've got a 60VA Transformer. At 230V I would protect that with 3.5 x 60VA = 210VA.
About 1A (Slow Blow) would protect the transformer.
About 1A (Slow Blow) would protect the transformer.
correct.
The transformer will run from a T21mA.
Well it won't because a 5VA transformer is very inefficient.
But it would probably run on a T40mA fuse.
Don't bother looking for a fuse that small, try T100mA or T250mA
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