SMPS problem

Hello
i have one application in which i have one SMPS
input 120 Volts 1.9 A (AC)
Output 12 Volts 8.5 A (DC)
what is rating for incomming fuse i shold put?

P = V x I DC
P = V x I AC

The SMPS will be Placed in Panel
what is rating for incomming fuse i shold put?

sandeeppatil1980,

Is this a "trick" question? Are you a student?

You did not say what the device SMPS actualy is, but I am guessing it is a 120 VAC to 12 volt DC Power Supply?

You should size your fuse based on the total power that will flow through the fuse. In your question that appears to be 1.9 Amperes, so allowing for Inrush current, I would use a 2.5 Amp fuse.

You did not say what the device SMPS actualy is

Click to expand...

SMPS - Switch Mode Power Supply

SMPS switching mode power supply

Well, guys I am proud to know what SMPS stands for (in YOUR opinions). I think it could mean that, and a million other things besides.

That is a complaint of mine. It takes so little time to spell out what you mean. When writers are sloppy and use abbreviations, especially here where there are members from all over the world, there can be much confusion and mis-intrerpretation. SMPS in one language or even just in one region of one country, can mean something different to someone else. Use jargon if you must, but know that you are risking being mis-understood.

sandeeppatil1980 did a better job asking his question over at Ron's site.

http://patchn.com/forum1/viewtopic.php?t=409

Lancie1 I wouldnt argue that, actually it has been discussed before.

As was mentioned I have seen the question before so knew what he was refering to so offered that information, just hapened not to be an opinion this time.

I offered this pdf file from Littlefuse to assist in determining the proper fuse:
http://www.littelfuse.com/data/en/Product_Catalogs/Chapter1IntroductiontoCircuitProtection.pdf

I think on my site some information was stated incorrectly. I originally stated that a 2amp fast blow fuse should be used, I still do....regardless of the components used on the secondary side. The transformer itself should not be subjected to current above its rating...that is my opinion.