Today's Message Index:
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1. 11:11 AM - SDS CPI-2 Circuit Protection Question (David Carter)
2. 04:57 PM - Re: SDS CPI-2 Circuit Protection Question (Charlie England)
3. 09:58 PM - What is a Shield Block Ground? (rparigoris)
Message 1
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| Subject: | SDS CPI-2 Circuit Protection Question |
I have the same question as the person that posted this:
https://vansairforce.net/community/showpost.php?p=1557258&postcount=85
Is there a good rationale for the separate fuses/breakers for the coil
power supply & the ECU supply?
---
David Carter
david@carter.net
Message 2
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| Subject: | Re: SDS CPI-2 Circuit Protection Question |
On 9/22/2021 1:10 PM, David Carter wrote:
> I have the same question as the person that posted this:
>
> https://vansairforce.net/community/showpost.php?p=1557258&postcount=85
> <https://vansairforce.net/community/showpost.php?p=1557258&postcount=85>
>
> Is there a good rationalefor the separatefuses/breakers for the coil
> power supply & the ECU supply?
>
> ---
> David Carter
> david@carter.net <mailto:david@carter.net>
I think that there is, for multiple reasons. 1st, the coil circuits are
*really* noisy. With a common wire feeding both, the noise has a direct
path into the supply for the ECU. (The 'filter' method, the battery,
would be a long ways away.) 2nd, if he's using the system fuse to
protect the cpu (not good practice, but many avionics makers have been
known to do it), 10A won't do it. 3rd (for me, anyway), I'd fuse each
coil block separately; not all coils on one fuse. All that separate
fusing means a single failure can't take out something else, like the
coil pack taking the ECU with it when the fuse blows. ATC/ATO fuse
blocks are relatively cheap and very compact for many circuits, so it's
easy to isolate each coil. If a coil goes shorted, separate fuses could
at least keep one pair of cylinders firing. Might make the difference
between the runway and the fence. (Failure modes effects analysis.)
One other thing that might be 'just me', but I would not put the engine
circuits on the main bus, or any airframe bus. My reasoning is,
training. Assuming that you have years of flying traditional a/c engines
under your belt, if you ever have the very rare but heavily trained-for
'smoke in the cockpit' situation, what's the first thing you're trained
do? Will you be able to override decades of trained-in muscle memory? I
doubt I could, so my engine stuff is on a separate, dedicated engine bus.
FWIW,
Charlie
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Message 3
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| Subject: | What is a Shield Block Ground? |
Hi Group In process of installing Garmin GDL 82 ADS-B. Page 10-1 and 10-2 speaks
of a Shield Block Ground for USB Type B Receptacle:
https://static.garmin.com/pumac/190-01810-00_06.pdf
What exactly is a Shield Block Ground?
Specifically on page 10-2 the triangle on the left side of the USB Type B Receptacle
that's pointing down, does it mean that it's not connected to anything?
Thx. Ron P.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=503260#503260
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