Protect the wiring yes, but my main concern is that one bad radio or other
device doesn’t take down the whole site.
From: Bill Prince
Sent: Wednesday, August 19, 2015 1:14 PM
To: af@afmug.com
Subject: Re: [AFMUG] medium blow fuses
I'm with Forrest. Stick to the fast blow.
Remember, fuses are not used to protect the equipment, they are used to protect
the wiring. Since it is "usually" faulty equipment causing the over current
condition, it is already probably toast anyway.
Just make the fuse large enough to handle the inrush without popping, and not
so large as to endanger your wiring.
bp
<part15sbs{at}gmail{dot}com>
On 8/19/2015 10:51 AM, Ken Hohhof wrote:
What got me on this track was discovering the replacement fuse for the Trango
ApexPlus/Lynx/Stratalink POE boxes is a 3.5 amp medium blow. It’s kind of
amusing because the single radio power supply they sell is only rated 1.5 amps,
so it can’t blow the fuse. But when I power it from a 6 amp Mean Well, the
fuse glows like a little incandescent bulb for a fraction of a second before
opening.
So I was just wondering if the medium blow fuses had their place. Some
distributors like Allied don’t even have them in their catalog, so I guess they
are a rare bird.
I also learned from perusing the spec sheets that fast blow fuses actually
take 30-60 minutes to blow until you get over 200% of rating, at 300% it comes
down to milliseconds. That probably explains George’s experience with 1/2A
fuses. But also with a 5A fuse on a Syncinjector, if the power supply can’t
put out at least 240 watts, things are going to cook for awhile before that
fuse blows.
From: Forrest Christian (List Account)
Sent: Wednesday, August 19, 2015 12:16 PM
To: af
Subject: Re: [AFMUG] medium blow fuses
A fast blow fuse is really very very slow when compared to electronics. I'd
recommend sticking with the fast blow fuses. If you're asking because you have
nuisance blows I might consider just moving up a amp or so depending on what
you're protecting.
On Aug 19, 2015 6:47 AM, "Ken Hohhof" <af...@kwisp.com> wrote:
I use fast blow 5x20 mm fuses for radios and other electronics, but
recently became aware that medium blow fuses exist. Not widely available, but
examples are Belfuse 530-5MT and Littelfuse 233 series.
So is anyone using these? Any advantage? I'm thinking devices that might
have enough inrush current to blow a fast blow fuse, although that hasn't been
a problem so far.
