In line fuse holder melting

[slowwilly]

12VDC circuit. In line blade style fuse holder. Fuse/holder connection is very tight (difficult to remove fuse). 20A fuse.

When examining this system several weeks ago, I noticed that the fuse/holder showed signs of overheating (some plastic & rubber melting) with the link in the fuse intact. I replaced it with a new holder & fuse.

I got a call from the customer. The fuse holder and fuse had burned up and melted. It melted at the fuse holder, not at the wire connections. I can replace it with another, but don't think I will get a different result.

This system is dual power. It runs off 12VDC truck battery/alternator or (via relays) a Meanwell S-320-12 voltage converter (when plugged in). The load is a fan motor.

Any thoughts on what might be causing this & what to do?

My understanding is that typically when a fuse holder melts, but doesn't blow the fuse, it would be because of loose connections. But due to the tight fit & the fact that we've used thousands of these holders in other applications without the converter, I'm thinking it might have something to do with the voltage converter.

 

[Comcokid]

Slowwilly-
What you are trying to do is not unique. AC to DC power converters are found in almost every RV on the road. But for RVs, they do not try to use regulated switch-mode supplies. Typically they use rectified 12V transformer supplies or Ferroresonant supplies. Maybe you should check as to what is available for the RV market, or do a google search to see if there is info in this market as to issues of running 12V fans from a AC-to-DC source.

 

[itsmoked]

Slowwilly;
Just for your info 4.5 watts on any component is a hellofalot if it isn't designed to dissipate it. Ever grabbed a blue Christmas tree sized lamp. (7-1/2 watts) It will fry you! A one watt resistor will unsolder itself if you actually stick a watt to it. Solder melts at what temp?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[MacGyverS2000]

"Solder melts at what temp?"

<raises hand> Ooh, ooh, I know, I know!

Oh, wait... is it eutectic?

Nevermind. The answer is "It melts at a temp hot enough to permanently remove my fingerprints should I be stupid enough to hang onto it long enough."

Dan - Owner

http://www.Hi-TecDesigns.com