Today's Message Index:
----------------------
1. 06:10 AM - Re: Re: FUSIBLE LINKS & CURRENT LIMITERS (Robert L. Nuckolls, III)
2. 07:07 AM - Re: Re: FUSIBLE LINKS & CURRENT LIMITERS (Charlie England)
3. 07:12 AM - Re: Re: FUSIBLE LINKS & CURRENT LIMITERS (Christopher Cee Stone)
4. 08:02 AM - Re: Re: FUSIBLE LINKS & CURRENT LIMITERS (Robert L. Nuckolls, III)
5. 10:16 AM - Re: Re: FUSIBLE LINKS & CURRENT LIMITERS (Christopher Cee Stone)
6. 12:35 PM - Re: FUSIBLE LINKS & CURRENT LIMITERS (fasilpereira)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
At 08:22 PM 4/23/2022, you wrote:
>Bob et al...
>
>Is there a min/max length for fusible links? With either fusible link wire or
>
>fabricated using the method described in "The Connection"?
The DIY fusible link was suggested about 20 years
ago when I was looking for a cleaner way to protect
ammeter shut instrument wires. BePiCesMo guys used
to favor a dual, glass cartridge fuse holder mounted
right at the shunt. Pieces of 4AWG smaller wire
under fiberglass seemed much neater.
Mind you, fusible links were already widely used
in the automotive world at this time but the bulk
wire was not readily obtainable nor had the idea
germinated in the aviation community for replacing
current limiters with specialty wire.
Fusible link wire has an interesting history. Waayy
back when, the electric locomotive industry was
looking for an insulation that minimized the
toxicity of smoke should a faulted wire burn.
Persons working in closed environments with very
high current wiring were at risk. Railroad and
mine locomotives (and I suspect submarines) were
prime markets for such a material.
I think it was DuPont that came up with a material
called "Hypalon" which has now has many competing
products. The smoke produced was more to the liking
of the Marlboro Man than the death row executioner.
We are now favored with a host of suppliers for
application specific fusible link wire. The
ability to eliminate the mechanically bulky
current limiters and certain fuses is attractive;
much simpler than the original DIY techniques
offered some years ago.
Keep in mind that fusible links (beefy and slow)
are NOT one-for-one replacements for fuses (agile
and fast). They are attractive alternatives to
current limiters.
I poked around on Youtube for examples of
fusible link replacement and did see one
example of very short (3" or so) factory
installed fusible links albeit poorly. The
Youtube author was replacing links where
joints had become intermittent due to
corrosion (!!!!). In our world, fusible link
installations should offer no greater risk
of failure than an equivalent hunk of quality
wire. The reason for having to make that
video was, in my not so humble opinion,
unforgivable. Just because the product sails
under the flag of a respected brand does not
automatically insure good craftsmanship.
As an aside, be wary of well meaning youtuber's
work product. I've gleaned many useful
insights from the works of DIY video producers.
I've also observed astounding ignorance of
the physics for the processes being demonstrated.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
>
> I saw a builder's contactors installation
> wherein he used fusible link wire to make
> a connection between the power posts on two
> contactors . . . no splice to extending
> wire.
>
>
> Bob . . .
>
Guilty. ;-)
The top pair of contactors control the B-leads of two internally regulated
alternators; the blue wires are fusible links to protect the red B-lead
wires seen leaving the contactors.
Without a long drawn-out explanation, the reason one is on the 'hot' side
of the master is that the plane has a fully electrically dependent engine;
I wanted access to an alternator even if the master contactor failed.
(Engine bus primary feeder is also fed from the hot side.)
Charlie
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
Bob et al...
I garner from your explanation that a fusible link of any length will
perform as intended. (To open a circuit).
But the longer length will open near the center due to localized thermal
characteristics.
Is there a downside to a shorter length other than it may burn through near
to or at the connection to
the feeder? Thus we want to avoid this condition?
Just trying to better understand the preferred opening mode.
If the feeder connection is robust then the fusible link will open
somewhere along its length
as its resistance is greater than that of the feeder. Regardless of
length.
It seems what we strive to avoid is heating and degradation of the feeder
wire
and/or connection during the over-current event?
Your expertise, experimentation and sharing of knowledge is very much
appreciated !
Chris
>
> Bob et al...
>
> Is there a min/max length for fusible links? With either fusible link wire
> or
>
> fabricated using the method described in "The Connection"?
>
>
> The DIY fusible link was suggested about 20 years
> ago when I was looking for a cleaner way to protect
> ammeter shut instrument wires. BePiCesMo guys used
> to favor a dual, glass cartridge fuse holder mounted
> right at the shunt. Pieces of 4AWG smaller wire
> under fiberglass seemed much neater.
>
> Mind you, fusible links were already widely used
> in the automotive world at this time but the bulk
> wire was not readily obtainable nor had the idea
> germinated in the aviation community for replacing
> current limiters with specialty wire.
>
> Fusible link wire has an interesting history. Waayy
> back when, the electric locomotive industry was
> looking for an insulation that minimized the
> toxicity of smoke should a faulted wire burn.
> Persons working in closed environments with very
> high current wiring were at risk. Railroad and
> mine locomotives (and I suspect submarines) were
> prime markets for such a material.
>
> I think it was DuPont that came up with a material
> called "Hypalon" which has now has many competing
> products. The smoke produced was more to the liking
> of the Marlboro Man than the death row executioner.
>
> We are now favored with a host of suppliers for
> application specific fusible link wire. The
> ability to eliminate the mechanically bulky
> current limiters and certain fuses is attractive;
> much simpler than the original DIY techniques
> offered some years ago.
>
> Keep in mind that fusible links (beefy and slow)
> are NOT one-for-one replacements for fuses (agile
> and fast). They are attractive alternatives to
> current limiters.
>
> I poked around on Youtube for examples of
> fusible link replacement and did see one
> example of very short (3" or so) factory
> installed fusible links albeit poorly. The
> Youtube author was replacing links where
> joints had become intermittent due to
> corrosion (!!!!). In our world, fusible link
> installations should offer no greater risk
> of failure than an equivalent hunk of quality
> wire. The reason for having to make that
> video was, in my not so humble opinion,
> unforgivable. Just because the product sails
> under the flag of a respected brand does not
> automatically insure good craftsmanship.
>
> As an aside, be wary of well meaning youtuber's
> work product. I've gleaned many useful
> insights from the works of DIY video producers.
> I've also observed astounding ignorance of
> the physics for the processes being demonstrated.
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
>Is there a downside to a shorter length other than it may burn
>through near to or at the connection to
>the feeder? Thus we want to avoid this condition?
>Just trying to better understand the preferred opening mode.
I'd like to believe that the manufacturer
of that automobile with 3" links tested their
design decision. Intuitively, one must believe
that the 'short' hunk of 4-AWG-Smaller wire is
a dominating weak-link that will indeed open
faster than the protected feeder.
>If the feeder connection is robust then the fusible link will open
>somewhere along its length
>as its resistance is greater than that of the feeder. Regardless of length.
>It seems what we strive to avoid is heating and degradation of the feeder wire
>and/or connection during the over-current event?
Agreed. I've got a couple of 100AH batteries
on my maintainer bench for a neighbor. One
of these would offer a really good energy source
for a fusible link demonstration/experiment. I'll
poke around and see if I can find all the 'stuff'
to lash this up.
>Your expertise, experimentation and sharing of knowledge is very
>much appreciated !
Thank you.
If one strives to advance the state of the
art and science, knowledge must be quantified,
shared, debated, refined and demonstrated. Lacking
any of these endeavors, the value of that
knowledge is diminished if not extinguished.
I've observed comments about the 'experimental'
nature of our work-product . . . "isn't that
a dangerous hobby?" they ask.
To the contrary, the advancement of every
art is a study in properties of materials,
management of energy and refinement of
process . . . experimentation is the very
essence of that last quality.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
>
> Looking forward to the result of your efforts in better understanding the
> properties of these devices
>
> ...Live to learn. Learning is a lifelong endeavor. Knowledge is a
social construct.
>
> Wisdom is gained by the application of curiosity, judgement and
reflection...
Chris
> To the contrary, the advancement of every
> art is a study in properties of materials,
> management of energy and refinement of
> process . . . experimentation is the very
> essence of that last quality.
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
Regarding those Fusible Link Wires, is there any source for a 24 AWG version of
it? I could only find it on 20AWG and up (or down? :D ) gauges.
I was looking insterested in installing it on the shunt sense wires, but I think
that using 16 AWG (20AWG minus 4AWG) an overkill...
Thank you,
Fabricio
--------
Fabricio Pereira
Engineer / Pilot
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506622#506622
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|