Fuses on the panel, or not

Anyone have any experience with the ETA - 1110-F112-P1M1-5A – circuit breaker/switch? Jonker used these on the early JS-1. See: http://www.newark.com/eta/1110-f112-...-5a/dp/98K5389

Tuesday, October 22, 2013 4:00:27 PM UTC-4, JohnDeRosa wrote:
On Sunday, October 20, 2013 12:31:32 PM UTC-5, Darryl Ramm wrote:



Capitalized ZERO, like you really mean absolutely zero, nothing, zilch, nada?

Ah in a word. No. A fuse will *not* have ZERO voltage drop. A typical fuse

for a few amp application might have a voltage drop of ~100mV to ~200mV drop

at the fuse rated current, and that depending on the fuse type and ratings).



Darryl - Mea Culpa. Yep, you got me on that one. Maybe I will do better this time.



Both fuses and breakers have an internal resistance which translates into a voltage drop (which depends on how much current you are drawing). Lets talk about a 1A load for nice round numbers (YMMV).



Littlefuse 3AG fuse specifications (common glass tube);



Rating Internal Voltage Drop Voltage Drop

Resistance at rated Current at 1A

==== ========== ================ ============

1A 0.19 0.19 0.19

2A 0.07 0.14 0.07

3A 0.04 0.13 0.04

4A 0.03 0.12 0.03

5A 0.02 0.11 0.02



Klixon CT series breaker specifications;



Rating Internal Volts Drop Voltage drop

Resistance at rating current at 1A

==== ========== ================ ============

1A 1.10 1.10 1.10

2A 0.35 0.70 0.35

3A 0.13 0.40 0.13

4A 0.09 0.37 0.09

5A 0.07 0.35 0.07



Take aways;



- Fuses have significantly lower voltage drops than breakers by an average of 4x ... but it AIN'T ZERO!

- The higher the current circuit protection device rating, the less voltage drop.

- Covering your panel with low rated fuses or breakers for each and every instrument isn't a good idea.

- Circuit protection devices in series with another device compounds the problem. For example a master fuse sourcing individual device fuses. Each layer drops more voltage.

- As had been said over and over again in this and other RAS threads, and bears repeating, a single large value fuse at the battery is your single best overall safety bet.

- One last thing - Per most manufacturers breakers should not be used as on/off switches. The only one I have found that can be used as an on/off switch is the Tyco W30 and W31 series.



- John

Ū1jd6

On a German forum earlier this year a Glider Instrument supplier started an enquiry to see if there would be any demand for a Centralised Power distribution unit. Forum is in German but the first message shows a picture and some description what they had in mind. I understand that the project was never realised as to many people had to many different demands.

http://forum.segelflug.de/showthread...zentraleinheit

At 14:02 31 October 2016, Muttley wrote:


On a German forum earlier this year a Glider Instrument supplier
started
an=
enquiry to see if there would be any demand for a Centralised Power
distri=
bution unit. Forum is in German but the first message shows a
picture and
s=
ome description what they had in mind. I understand that the project
was
ne=
ver realised as to many people had to many different demands.

http://forum.segelflug.de/showthread.php?
t=3D8160&highlight=3Dzentraleinhei=
t

please use this url

http://tinyurl.com/z7678rz

Using either URL, I was asked in German to create an account, which I'm
not willing to do. How about copying and posting the picture?

On 10/31/2016 8:26 AM, Bruno Ramseyer wrote:
At 14:02 31 October 2016, Muttley wrote:

On a German forum earlier this year a Glider Instrument supplier
started
an=
enquiry to see if there would be any demand for a Centralised Power
distri=
bution unit. Forum is in German but the first message shows a
picture and
s=
ome description what they had in mind. I understand that the project
was
ne=
ver realised as to many people had to many different demands.

http://forum.segelflug.de/showthread.php?
t=3D8160&highlight=3Dzentraleinhei=
t
please use this url

http://tinyurl.com/z7678rz


--
Dan, 5J

On Sunday, October 20, 2013 at 3:48:31 PM UTC-6, Darryl Ramm wrote:



Folks might also want to note the requirement in CFR 14 23.1357 for the fuses to be replaceable in flight if critical and the need to carry spares. So you might be able to argue that some non-critical fuses can be placed behind the panel but others will clearly fail that requirement. I'd not want to argue with the FAA for example that the fuel pump or engine controller fuse holders and replacement fuses in a motorglider don't need to be accessible to the pilot.

For Day VFR there is nothing "Citical". Granted, the FAA has gone back and forth on this over the years but I think this is being a bit overthought.

Also see FAA AC 43.13 Acceptable Methods, Techniques, and Practices -
And... if working on any aircraft start with talking with a local A&P (or maybe an EAA homebuilder or similar), if certified they'll need the A&P will need to sign off on what you do (or do it for you), if experiential you want their advice and likely a look over what you are planning to do/have done. There is a lot to gain by actually having somebody look over your shoulder that you can't get off r.a.s.

AC43 is great but it tends to not address gliders (That do not have engine driven electrical systems). A big example is common grounding VS airframe ground. This can be a tough sell if your A&P is not familiar with gliders. Another biggie is the use of non aviation grade (Or car parts). If your glider was built of certificated in Europe it has a lot of off the shelf componentry. This can also be an issue to some mechanics not familiar with gliders.

On Monday, October 31, 2016 at 5:37:45 PM UTC, Dan Marotta wrote:
Using either URL, I was asked in German to create an account, which I'm
not willing to do. How about copying and posting the picture?

On 10/31/2016 8:26 AM, Bruno Ramseyer wrote:
At 14:02 31 October 2016, Muttley wrote:

On a German forum earlier this year a Glider Instrument supplier
started
an=
enquiry to see if there would be any demand for a Centralised Power
distri=
bution unit. Forum is in German but the first message shows a
picture and
s=
ome description what they had in mind. I understand that the project
was
ne=
ver realised as to many people had to many different demands.

http://forum.segelflug.de/showthread.php?
t=3D8160&highlight=3Dzentraleinhei=
t
please use this url

http://tinyurl.com/z7678rz


--
Dan, 5J

You can see a picture here
https://drive.google.com/open?id=0B9...zlISDl6am1tSU0

I have a Microair transponder which has some type of an internal electrical circuit that uses on shutdown. In cases of low voltage it simply will not shut down. In a couple of instances after very long flights I was getting to critically low battery voltage and was going through a sequenced shut down of equipment. When I got to the Microair, it would not shut down because of the low voltage. Fortunately I had the fuse on the panel and with my thumbnail could shut it down that way.
For what it's worth,
Roy
On Monday, October 14, 2013 at 8:10:12 PM UTC-4, SF wrote:
My big winter glider project is going to be re-doing my control panel. I have been looking at a lot of panel pictures recently and I notice that a lot of them have panel mounted fuse holders all over them. My experience with our panel mounted electronic gizmos is that if they blow a fuse, replacing it inflight is not going to do anything for you. Once the magic smoke gets out it's gone. So I'm looking at a terminal strip that incorporates the mini blade type fuses into the strip, and reducing the number of holes in the panel.

Has anyone ever replaced a glider fuse in flight and had something good happen?

SF

On Tuesday, November 1, 2016 at 8:27:11 AM UTC-7, wrote:
On Sunday, October 20, 2013 at 3:48:31 PM UTC-6, Darryl Ramm wrote:



Folks might also want to note the requirement in CFR 14 23.1357 for the fuses to be replaceable in flight if critical and the need to carry spares.. So you might be able to argue that some non-critical fuses can be placed behind the panel but others will clearly fail that requirement. I'd not want to argue with the FAA for example that the fuel pump or engine controller fuse holders and replacement fuses in a motorglider don't need to be accessible to the pilot.

For Day VFR there is nothing "Citical". Granted, the FAA has gone back and forth on this over the years but I think this is being a bit overthought.

Also see FAA AC 43.13 Acceptable Methods, Techniques, and Practices -
And... if working on any aircraft start with talking with a local A&P (or maybe an EAA homebuilder or similar), if certified they'll need the A&P will need to sign off on what you do (or do it for you), if experiential you want their advice and likely a look over what you are planning to do/have done. There is a lot to gain by actually having somebody look over your shoulder that you can't get off r.a.s.

AC43 is great but it tends to not address gliders (That do not have engine driven electrical systems). A big example is common grounding VS airframe ground. This can be a tough sell if your A&P is not familiar with gliders. Another biggie is the use of non aviation grade (Or car parts). If your glider was built of certificated in Europe it has a lot of off the shelf componentry. This can also be an issue to some mechanics not familiar with gliders.


If your A&P wants to use airframe ground on your composite glider, get yourself a new A&P:-)

I use MIL-Spec 3A Klixon breakers on the panel and the Dittel battery box came with its own built in breaker. I only saw about 0.2VDC drop across the Klixon breakers.

14, 2013 at 8:10:12 PM UTC-4, SF wrote:
My big winter glider project is going to be re-doing my control
panel. I have been looking at a lot of panel pictures recently and
I notice that a lot of them have panel mounted fuse holders all
over them. My experience with our panel mounted electronic gizmos
is that if they blow a fuse, replacing it inflight is not going to
do anything for you. Once the magic smoke gets out it's gone. So
I'm looking at a terminal strip that incorporates the mini blade
type fuses into the strip, and reducing the number of holes in the
panel.

Has anyone ever replaced a glider fuse in flight and had something
good happen?

About 20 years ago, I replaced a vario fuse in flight, but that's been
the only one in 40 years of glider flying. The vario worked fine, and I
have no idea why the fuse blew. A few years ago, I put the instruments
on mini ATM fuses in a block behind the panel, and I like that arrangement.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf