I understand the intuition that a fuse ought to be fast. It seems simple,
right ? No moving parts.
However.....
It is a thermodynamic device. It requires that the metal in the fuse be
heated for a period of time until the latent heat of fusion is supplied to
the mass of metal. Then the metal will change from the solid to the liquid
phase, and the fuse opens. Metal has a pretty high value, in BTU/lbm, of
heat of fusion. Thus, the current has to flow for an appreciable time until
the proper amount of heat is supplied. It isn't just temperature, it is
total amount of heat in BTU's, at that temperature.
Thus, each device takes some time, neither is instantaneous. And the
air-pax are known to be better and that is why Ten Tec wants us to use them.
They would certainly have specified (and supplied) fuses instead, if they
were what was better.
And I agree....time for end of thread. My last post on this also.
73 de Gary, AA2IZ
----- Original Message -----
From: "Ken Brown" <ken.d.brown@hawaiiantel.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Sunday, June 18, 2006 3:08 PM
Subject: Re: [TenTec] Using Airpax breaker
> Specifications for both fuses and circuit breakers are probably
> available, which would include the amount of time that it take to
> transition from closed to open after an over current condition begins.
> When I think about the mechanics of a circuit breaker versus a fuse, and
> the amount of mass which has to move in order for the path to open in a
> circuit breaker versus a fuse, I find it easier to believe that the fuse
> is faster. Some very smart engineers have put a lot of effort into
> designing both fuses and circuit breakers, and it may be the results of
> their efforts contradict my intuitive sense that a fuse opens faster.
> Comparison of specification sheets ought to settle it.
>
> Ken N6KB
>
> Tommy wrote:
> > Hi Art,
> >
> > I agree with you Art. It is true this should not become a 'fuss'
> > because Mike is correct and your statement is simply incorrect. End
> > of story. Period!
> >
> > Happy Fathers Day.....
> >
> > Tom - W4BQF
> >
> >
> >
> > At Sunday 09:56 AM 6/18/2006, you wrote:
> >
> >> Sorry Mike you are very very wrong. Fuses are always used when one
> >> wants the best protection for solid state equipment or even in large
> >> industrial applications for motors etc they are mandatory. But I
don't
> >> plan on getting into an on line fuss so this is my last email on the
> >> subject. If anyone is interested just do a google search.
> >>
> >> Best
> >>
> >> Art
> >>
> >>
> >>
> >>
> >> Mike Hyder -N4NT- wrote:
> >>
> >>> Because I believe that people have the right to be wrong, I normally
> >>> wouldn't respond to this. Art is 100% wrong. I want nobody to lose a
rig
> >>> because of his advice. The Air-Pax circuit breakers are much faster
than
> >>> fuses. A fuse will not separate quick enough to reliably protect a
rig.
> >>>
> >>> About how to connect them: I crimp the spade connectors to the wires
and
> >>> slide them onto the contacts of the Air-Pax. I do not know the
> >>>
> >> best way but
> >>
> >>> my way works find and runs no risk of heat damage to the breaker.
> >>>
> >>> 73, Mike N4NT
> >>>
> >>> ----- Original Message -----
> >>> From: "Rideout Family" <wa6ipd@dslextreme.com>
> >>> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> >>> Sent: Sunday, June 18, 2006 5:29 AM
> >>> Subject: Re: [TenTec] Using Airpax breaker
> >>>
> >>>
> >>>
> >>>
> >>>> If you are looking for over current protection fuses are the way to
go
> >>>> they can clear in 1/2 cycle or less. Circuit breakers are mechanical
> >>>> devices with moving parts, and break the circuit too slowly.
> >>>>
> >>>> Art,
> >>>> WA6IPD
> >>>>
> >>>>
> >>>>
> >>>> Kirk Braunius wrote:
> >>>>
> >>>>
> >>>>> How do some of you on the list mount Airpax breakers in a power line
> >>>>> between
> >>>>> p/s and radio? I'm planning on putting mine in a small metal box.
Do
> >>>>> you
> >>>>> attach spade connectors to your power line and slip onto breaker, or
> >>>>> solder
> >>>>> directly to the breaker? If soldering, what kind of mechanical
> >>>>> connection
> >>>>> do you start with?
> >>>>>
> >>>>> Thanks,
> >>>>> Kirk
> >>>>> AI4PZ
> >>>>>
> >>>>>
> >>> _______________________________________________
> >>> TenTec mailing list
> >>> TenTec@contesting.com
> >>> http://lists.contesting.com/mailman/listinfo/tentec
> >>>
> >>>
> >>>
> >>>
> >> _______________________________________________
> >> TenTec mailing list
> >> TenTec@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/tentec
> >>
> >
> > Tom
> >
> > "I couldn't repair your brakes, so I made your horn louder."
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
> >
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>
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