Today's Message Index:
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1. 12:41 PM - Re: FUSIBLE LINKS & CURRENT LIMITERS (Robert L. Nuckolls, III)
2. 04:00 PM - Re: FUSIBLE LINKS & CURRENT LIMITERS (johnbright)
3. 06:23 PM - Re: Re: FUSIBLE LINKS & CURRENT LIMITERS (Christopher Cee Stone)
4. 07:48 PM - Re: FUSIBLE LINKS & CURRENT LIMITERS (johnbright)
Message 1
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| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
At 06:25 PM 4/22/2022, you wrote:
>Thanks Bob. Appreciate the explanations. I suspected the fusible
>link is used due to it being
>more resilient or as you say slower to operate.
In general, fuses and circuit breakers are more sensitive to
moderate overload and will operate in seconds to tens of seconds.
Current limiters (ANL, ANN, MAN, etc) look like fuses but thermally
tailored to withstand high transient loads. They are generally used
to protect feeders to downstream protection like fuses and/or
circuit breakers where you don't want the upstream protection
to operate because of a hard fault on one of the individually
protected, downstream feeders. Fusible links fall into that
same category of protection.
>And you answered my follow up question before I could ask it.
>If a slow operating device is preferred, why not use a slow blow fuse?
That's essentially what a current limiter is . . . it's
a fuse with a 2 to 3 times overhead for operating current
and a much longer thermal time constant.
>Fusible link easy to install compared to the clumsy fuse. Duly noted.
Yup. You can now buy fusible link wire in the automotive
parts stores . . . ordinary copper wire insulated with
Hypalon or similar insulation resistant to toxic destruction
due to melting wire within. Neat stuff.
https://tinyurl.com/yy7xy8wd
>But in diagram Z12 I still don't see a fusible link in the circuit
>that feeds the alternator field. What am I missing? I see a 5A
>field breaker at the main power buss. From there a 20AWG wire feeds
>tab 5 of the master switch. From tab 4 of the master switch a 20AWG
>wire feeds pin 6 of the B and C LR-3 controller. A 20AWG wire from
>pin 4 of the controller feeds the alternator field. I don't see a
>fusible link in this circuit as I do in diagram Z11. The system in
>Z11 uses fuses and Z12 used CB's. Does this make any difference?
Here are the relevant excerpts from Z-11 and Z-12. There's
a fusible link upstream of alternator field breakers
in both diagrams. Z-11 is an older drawing that suggests
a '4AWG-smaller', DIY fusible link while Z-12
suggests commercial-off-the-shelf, fusible link wire.
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
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| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
nuckolls.bob(at)aeroelect wrote:
> Hi Bob,
>
> ... help me understand the fusible link between the buss and master switch in
Z11, but there is no fusible link in this circuit in Z12.
The latest Z12 rev N shows a fuse link for the feeder from main bus to field CB.
The previous rev M which is in the latest AeroElectric Connection book rev 12B
shows the field CB directly on the bus. Fuseblock or busbar and CBs (acres
of breakers)... it's a culture war and Bob in in the fuseblock camp. I'm guessing
the older Z12 reflects a production aircraft.
Find the latest Z templates in the Adobe folder at http://www.aeroelectric.com/PPS/
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
https://drive.google.com/folderview?id=1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506602#506602
Message 3
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| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
> 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"?
...chris
>
> In general, fuses and circuit breakers are more sensitive to
> moderate overload and will operate in seconds to tens of seconds
>
>
> That's essentially what a current limiter is . . . it's
> a fuse with a 2 to 3 times overhead for operating current
> and a much longer thermal time constant.
>
> Fusible link easy to install compared to the clumsy fuse. Duly noted.
>
>
> Here are the relevant excerpts from Z-11 and Z-12. There's
> a fusible link upstream of alternator field breakers
> in both diagrams. Z-11 is an older drawing that suggests
> a '4AWG-smaller', DIY fusible link while Z-12
> suggests commercial-off-the-shelf, fusible link wire.
>
>
> 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
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| Subject: | Re: FUSIBLE LINKS & CURRENT LIMITERS |
rv8iator wrote:
> Is there a min/max length for fusiblelinks?Witheither fusiblelink wire or fabricated
using the method described in "The Connection"?
>
> ...chris
Note 4 says 4 to 6" and http://www.aeroelectric.com/articles/fuselink/fuselink.html says 5 to 6".
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
https://drive.google.com/folderview?id=1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506605#506605
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