Determine Fuse in power supply
Determine Fuse in power supply
(OP)
Hi all,,
I have question about determine fuse,
I would like to build power supply which the output is 12V@25A and 5V@1A
I will try to build linear power supply,
My transformer is 220V -> 24V (500VA).
Could you tell me what is the fuse value should be?
Thank you
regards
I have question about determine fuse,
I would like to build power supply which the output is 12V@25A and 5V@1A
I will try to build linear power supply,
My transformer is 220V -> 24V (500VA).
Could you tell me what is the fuse value should be?
Thank you
regards





RE: Determine Fuse in power supply
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Determine Fuse in power supply
Keith Cress
kcress - http://www.flaminsystems.com
RE: Determine Fuse in power supply
Calculate your in-rush current when the supply first starts up. Make sure the I^2*T value support this current for a long enough time (typically a half cycle of the mains frequency for a switcher, probably longer for a linear). This sets your minimum fuse value.
At that point you can select any value in between these limits to meet other requirements.
John D
RE: Determine Fuse in power supply
The transformer rated current = 500VA/220V = 2.27A
A value such as 3A or 4A time delay should be OK and allow for transformer inrush.
You might also need other protection inside the supply. If one of the outputs is shorted or components fail shorted you do not want parts to burst into flames.
On another note, your transformer is too small for the linear supply you want to build. 24VAC rectifies to about 28VDC. 12V @ 25A with a linear rectifier will require you to pull 25A off the raw 28VDC. 28V x 25A = 700VA.
RE: Determine Fuse in power supply
RE: Determine Fuse in power supply