Fuses on the panel, or not

[SF]

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

[SoaringXCellence]

In a recent safety bulletin from the FAA, they noted that inflight resetting of circuit breakers should mostly be avoided and that in any case they should only be reset once and thereafter left triggered if it happens again; delaying further troubleshooting until the flight is completed. They suggest the tripped circuit breakers, found during a pre-flight, should not be reset without investigation by airframe or avionic technicians.

Fuses are not discussed, but the principle of protecting the main electrical system from a failed sub-system still applies. If it occurs in flight, do your best to do without it for the remainder of the flight.

Recently I was powering up a PIK-20 and after a few moments there was a smell of burning insulation and I powered the system off. In the following inspection we discovered that the VolkLogger had shorted and the complete harness from the VL to the power distribution had basically melted. The circuit was protected by a 2 Amp fuse that did blow but I have to believe there was much more than 2 Amps flowing to melt that wiring before the fuse melted.

I'm just delighted that it didn't happen after I was aloft. I might have not smelled the burnt wiring if there had been some airflow through the cockpit. Might have lite something else up before I know it.

We are planning on rebuilding the whole panel/electrical system this winter and I'll do some serious measuring before selecting the fuse current values. I'd rather the fuse blew early that late.

Mike

[Paul Ruskin[_2_]]

When I did mine I used a lot of solid state fuses to protect all the circuits. They'e a little device that if too much current flows they go high resistance. Take the fault away and they go back to low resistance. Most of mine are mounted on a circuit board behind the panel - so no panel space issues.

Paul

On Tuesday, October 15, 2013 5:15:26 AM UTC+1, SoaringXCellence wrote:
> In a recent safety bulletin from the FAA, they noted that inflight resetting of circuit breakers should mostly be avoided and that in any case they should only be reset once and thereafter left triggered if it happens again; delaying further troubleshooting until the flight is completed. They suggest the tripped circuit breakers, found during a pre-flight, should not be reset without investigation by airframe or avionic technicians.
>
>
>
> Fuses are not discussed, but the principle of protecting the main electrical system from a failed sub-system still applies. If it occurs in flight, do your best to do without it for the remainder of the flight.
>
>
>
> Recently I was powering up a PIK-20 and after a few moments there was a smell of burning insulation and I powered the system off. In the following inspection we discovered that the VolkLogger had shorted and the complete harness from the VL to the power distribution had basically melted. The circuit was protected by a 2 Amp fuse that did blow but I have to believe there was much more than 2 Amps flowing to melt that wiring before the fuse melted.
>
>
>
> I'm just delighted that it didn't happen after I was aloft. I might have not smelled the burnt wiring if there had been some airflow through the cockpit. Might have lite something else up before I know it.
>
>
>
> We are planning on rebuilding the whole panel/electrical system this winter and I'll do some serious measuring before selecting the fuse current values. I'd rather the fuse blew early that late.
>
>
>
> Mike

[Jim White[_3_]]

I agonised over this when I re did my own panel. My conclusions were:

1) I would not reset or replace a fuse in flight so did not need them on
the panel.

2) Thermal trips need a large overcurrent for a long time before they go.
Low value trips introduce a large voltage drop.

So, I fitted in line blade fuses for all my equipment and use the panel
space for other things. I did buy a fuse block but decided it was too big
and made the wiring cumbersome.

Jim

[Peter Purdie[_3_]]

Fuses rely on getting hot enough to melt the wire. Quick blow can easily go
on initial surge, and need considerably above the rating to blow on
continuous current. Slow blow take about the same length of time and
overcurrent as a thermal circuit breaker. Both thermal c/bs and fuses drop
voltage - that's how they get hot.

Magnetic trip breakers drop less voltage, and have a more precise trip, but
cost 2 - 3 times the price.

Fuses are to protect the wiring, if the wiring burns before the fuse blows
then the wire is much too low rated.

Personally I use breakers, and appropriate gauge wiring. It means I don't
have to have a bunch of spare fuses handy. Murphy guarantees that a fuse
will blow just before take off on the best day of the year, and that
someone wil have 'borrowed' the little bag of spare fuses.


At 08:23 15 October 2013, Jim White wrote:
>I agonised over this when I re did my own panel. My conclusions were:
>
>1) I would not reset or replace a fuse in flight so did not need them on
>the panel.
>
>2) Thermal trips need a large overcurrent for a long time before they go.
>Low value trips introduce a large voltage drop.
>
>So, I fitted in line blade fuses for all my equipment and use the panel
>space for other things. I did buy a fuse block but decided it was too big
>and made the wiring cumbersome.
>
>Jim

[jfitch]

On Monday, October 14, 2013 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

I have replaced a fuse in flight. The fuse was fine, the socket was not making contact so just pulling it out and putting it back fixed it. I am searching for some panel mount magnetic breakers that will install in the same space and on the same pitch as the fuse holders.

[7C]

> 2) Thermal trips need a large overcurrent for a long time before they go.
> Low value trips introduce a large voltage drop.

I would add to this that thermal trips will reset after a period of time. If the original short persists they will cycle on and off quite quickly (in my experience a few times a second) and will NOT protect equipment from overheating. I had them on my batteries and got lucky to that the output to the 5V converter shorted on the ground - the 12 to 5v converter overheated, caused a permanent short and ended up well above too hot to touch. I now have a normal fuse and redundancy provided by a second battery.

I would be concerned that any self-resetting circuit would behave the same, perhaps with a longer cycle. If you can't physically isolate then you are stuffed when you are flying... Bet you can't land quickly enough

[son_of_flubber]

On Tuesday, October 15, 2013 11:39:59 AM UTC-4, 7C wrote:
> If you can't physically isolate then you are stuffed when you are flying.... Bet you can't land quickly enough <

Someone told me a story about bad smoke developing in the cockpit of a glider. The pilot ejected the canopy. At that point the increased airflow stoked the smoldering fire and something burst into flames. Story goes, he landed and the fire went back to smoldering.

Does this sound plausible or is it yet another BS story?

[Matt G.]

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

SF

Not 'replaced,' but 'removed.' On the first flight of my Austria after I restored it, the landing gear warning circuit malfunctioned and the horn came on and stayed on regardless of airbrake position (with the gear down). I pulled the fuse so I could concentrate on landing without that awful noise.

[Dan Marotta]

You might label the fuse holder so that you don't have to read the fuse. Be
sure to install the correct fuse...


<snip>
>
> Have you ever tried to read the fuse type engraved on the ferule, on a
> turbulent day while maintaining a good lookout (let's assure the fuse
> controlling FLARM has blown)?
> --

[Dan Marotta]

More air flow can fan or extinguish a fire.

In his shoes, I'd have stepped over the side. I'd really hate to have a
major part of the glider burn away while on final approach!


"son_of_flubber" > wrote in message
...
On Tuesday, October 15, 2013 11:39:59 AM UTC-4, 7C wrote:
> If you can't physically isolate then you are stuffed when you are
> flying... Bet you can't land quickly enough <

Someone told me a story about bad smoke developing in the cockpit of a
glider. The pilot ejected the canopy. At that point the increased airflow
stoked the smoldering fire and something burst into flames. Story goes, he
landed and the fire went back to smoldering.

Does this sound plausible or is it yet another BS story?

[JohnDeRosa]

A couple of comments about circuit protection some of which has been covered before in other threads;

- Pete Purdie's comment above about undersized wiring is on target. Bigger is better (within reason)! If you saw smoke you probably do not have Tefzel wiring. Get some!
- Fuses are great as they are cheap, fast acting and have ZERO voltage drop across its terminals. Cons are that they are more difficult to replace in flight and somewhat fragile (glass type).
- Breakers are great as they are easy to reset in flight. Cons are that they are expensive, somewhat slow acting and will cause a voltage drop across its terminals. This voltage drop effect is worse at small breaker values, you can loose 1/2 volt or more. That is fine for ships with generators but lousy for gliders.
- Put a FUSE on each battery at the terminals. This is the absolute minimum circuit protection you MUST have.

So if you really want separate protection for each of your devices, then use small value fuses rated just above the maximum current for each piece of hardware. Otherwise go with a large value single breaker to protect the entire system.

As to the use of different types of fuses (glass versus blade type) this relates more to what your IA will sign off. Blade type are certainly more robust and I saw them in lots of experimental airplanes at Oshkosh. But the FAA is a strange and demanding mistress. ;-)

My $0.02. Good luck.

- John

[Dave Nadler]

Please don't install glass fuses, because they are prone to:
- blowing under vibration (like, rolling during launch)
- even more prone to blowing in gas-powered motorgliders
- corroding and introducing voltage drop at the (non-gas-tight) ends
The voltage drop breakers introduce can be significant and can cause problems.
Use blade types inline (not on the panel!) and avoid these problems...
Hope that helps,
Best Regards, Dave "YO electric"

[[email protected]]

I have just finished designing my new panel and will now place all fuses behind the panel. The reasons are 1) I want a very clean panel and 2) in the past 600h of flight i never had to reset a fuse, and i wouldn't do so if it blew. The only thing you must make sure is to have a possibility to shut off power in case of smoke/fire (master switch).

[Dan Marotta]

....And be sure to have an appropriate sized fuse as close to the battery
terminals as possible.


> wrote in message
...
I have just finished designing my new panel and will now place all fuses
behind the panel. The reasons are 1) I want a very clean panel and 2) in the
past 600h of flight i never had to reset a fuse, and i wouldn't do so if it
blew. The only thing you must make sure is to have a possibility to shut off
power in case of smoke/fire (master switch).

[[email protected]]

Regarding mini-blade type fuses, my searching has yet to locate a reasonable sized mini-fuse block as well as not being able to locate mini-blade fuses in low amp values. IMSMC, 2 amp was the smallest value I could find cataloged from DigiKey or Mouser.

I would appreciate a steer to any small mini-blade fuse blocks or low amp mini-fuses.

[James Lee]

On Friday, October 18, 2013 11:23:28 AM UTC-4, wrote:
> Regarding mini-blade type fuses, my searching has yet to locate a reasonable sized mini-fuse block as well as not being able to locate mini-blade fuses in low amp values. IMSMC, 2 amp was the smallest value I could find cataloged from DigiKey or Mouser.
>
>
>
> I would appreciate a steer to any small mini-blade fuse blocks or low amp mini-fuses.

Take a look at these motorcycle fuse blocks- http://www.easternbeaver.com/Main/main.html

[son_of_flubber]

On Friday, October 18, 2013 11:23:28 AM UTC-4, wrote:

> I would appreciate a steer to any small mini-blade fuse blocks or low amp mini-fuses.

https://www.google.com/search?q=1amp+blade+fuse&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

[John Galloway[_1_]]

My preference is for individual equipment CBs to be on the panel
and visible (rather than hidden fuses or CBs) to help with in flight
diagnosis in the event of an instrument or equipment power loss.

In some cases I might try a reset - I did so succesfully once when
the turbo pylon CB popped with the engine half retracted. I
would probably reset a bugwiper CB too. Delicate intruments -
not so likely. Nor if the cockpit were to be getting smokey.

John Galloway

At 21:49 16 October 2013, wrote:
>I have just finished designing my new panel and will now place
all fuses
>be=
>hind the panel. The reasons are 1) I want a very clean panel
and 2) in the
>=
>past 600h of flight i never had to reset a fuse, and i wouldn't do
so if
>it=
> blew. The only thing you must make sure is to have a possibility
to shut
>o=
>ff power in case of smoke/fire (master switch).
>

[son_of_flubber]

Some dumb questions, but these things sometimes don't work like I imagine they would.

Say I have a 3 amp fuse at the battery and a 1 amp blade fuse in series and the one amp feeds power to a single instrument. (with other 1 amp fuses going to other devices)

Is there a scenario where a 1 amp blows and the 3 amp does not? I figure that most shorts will draw more than 3 amps and blow both fuses. Do devices develop "partial shorts"?

Is there a scenario where both fuses blow?

Would it make sense to make the 3 amp "slow blow" and the 1 amp "normal blow"?

What am I missing?

[JS]

For a very clean power distribution option, have a look at

http://www.powerwerx.com/powerpole-power-distribution/

Anderson 15A Powerpole connections for all the instruments, with blade fuses on master and all outputs.
Alternatively, there are fused Power Distribution blocks without Powerpoles on the "fuses & circuit protection" page.
Jim

On Friday, October 18, 2013 8:23:28 AM UTC-7, wrote:

> I would appreciate a steer to any small mini-blade fuse blocks or low amp mini-fuses.

[son_of_flubber]

On Saturday, October 19, 2013 3:34:50 PM UTC-4, JS wrote:
> For a very clean power distribution option, have a look at
>
>
>
> http://www.powerwerx.com/powerpole-power-distribution/

Aside from the expense what about http://www.powerwerx.com/powerpole-power-distribution/rigrunner-4005h-horizontal.html

and also assuming you have space for this near the instruments.

[[email protected]]

On Wednesday, October 16, 2013 5:26:48 PM UTC-4, Dave Nadler wrote:
> Please don't install glass fuses, because they are prone to:
>
> - blowing under vibration (like, rolling during launch)
>
> - even more prone to blowing in gas-powered motorgliders
>
> - corroding and introducing voltage drop at the (non-gas-tight) ends
>
> The voltage drop breakers introduce can be significant and can cause problems.
>
> Use blade types inline (not on the panel!) and avoid these problems...
>
> Hope that helps,
>
> Best Regards, Dave "YO electric"

Can blade fuses be installed in type certified gliders?

[Darryl Ramm]

On Tuesday, October 15, 2013 8:39:59 AM UTC-7, 7C wrote:
> > 2) Thermal trips need a large overcurrent for a long time before they go.
>
> > Low value trips introduce a large voltage drop.
>
>
>
> I would add to this that thermal trips will reset after a period of time. If the original short persists they will cycle on and off quite quickly (in my experience a few times a second) and will NOT protect equipment from overheating. I had them on my batteries and got lucky to that the output to the 5V converter shorted on the ground - the 12 to 5v converter overheated, caused a permanent short and ended up well above too hot to touch. I now have a normal fuse and redundancy provided by a second battery.
>
>
>
> I would be concerned that any self-resetting circuit would behave the same, perhaps with a longer cycle. If you can't physically isolate then you are stuffed when you are flying... Bet you can't land quickly enough

Uh? Why are you talking about "thermal trips" and automatic resetting? These thingies are called circuit breakers. Yes they they internally thermally trip, but so what. An aviation circuit breaker like the popular Klixon "TC" product lines will not automatically reset. You've got to push 'em back in.. For good reason.

Darryl

[Darryl Ramm]

On Wednesday, October 16, 2013 12:42:06 PM UTC-7, JohnDeRosa wrote:
> A couple of comments about circuit protection some of which has been covered before in other threads;
>
>
>
> - Pete Purdie's comment above about undersized wiring is on target. Bigger is better (within reason)! If you saw smoke you probably do not have Tefzel wiring. Get some!
>
> - Fuses are great as they are cheap, fast acting and have ZERO voltage drop across its terminals. Cons are that they are more difficult to replace in flight and somewhat fragile (glass type).

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 fuse relies on resistance in the fuse element causing heating and mechanical failure of the element. A typical fuse for a few amp applciation might have a voltage drop of ~100mV to ~200mV drop at the fuse rated current, and that depending on the fuse type and ratings). If there was zero resistance the fuse would never work. Since there is resistance there will be a voltage drop. Now that voltage drop may be a lot less than a similar spec circuit breaker, especially for low trip current applications. And in both cases is not a simple linear relationship, vendors typically provide voltage drop as a part of the spec sheet of their fuses and breaker products and fuse specs will include both that drop at rated current and a cold resistance value.

[[email protected]]

On Tuesday, October 15, 2013 1:23:20 AM UTC-7, Jim White wrote:
> I agonised over this when I re did my own panel. My conclusions were:
>
> 1) I would not reset or replace a fuse in flight so did not need them on
> the panel.
>
> 2) Thermal trips need a large overcurrent for a long time before they go.
> Low value trips introduce a large voltage drop.
>
> So, I fitted in line blade fuses for all my equipment and use the panel
>
> space for other things. I did buy a fuse block but decided it was too big
>
> and made the wiring cumbersome.
>
> Jim

I bought and tested Klixon CBs and the standard German panel mounted fuses when I re-did my panel last winter. The CBs had a significant voltage drop - corresponding to about 20 minutes of battery life at the end of a flight if I recall correctly. I was unwilling to give up the extra duration off my battery, so I stayed with fuses.

My panel is curved and my instruments are basically square behind the panel so there were several good triangular-shaped spots that could accommodate up to 5 panel-mounted fuse holders. I have never replaced a fuse in flight, but I could imagine a circumstance where a current spike (maybe from keying the radio) could blow a fuse that I might want to replace. Plus it's easier not to have to take off the canopy to get behind the panel. I've seen fuses mounted in the leg tunnel under the panel, which is an interesting alternative.

I'm a little nervous about putting automotive parts in my glider - for instance, I replaced all my wiring with Tefzel after experimenting with high current through the vinyl shielded Radio Shack variety.

9B

[Dave Nadler]

On Sunday, October 20, 2013 2:11:39 PM UTC-4, wrote:
> I'm a little nervous about putting automotive parts in my glider

You mean, for example, old-style automotive glass fuses, given
up by the auto industry as too unreliable some decades ago ???

Please do not put ANYTHING from RadioShack in a glider panel...

[Dave Nadler]

On Sunday, October 20, 2013 1:07:38 PM UTC-4, Darryl Ramm wrote:
> Uh? Why are you talking about "thermal trips" and
> automatic resetting?

Hi Darryl - I think he's talking about PTCs, which are
appropriate in some situations but not here...

[Darryl Ramm]

On Sunday, October 20, 2013 12:23:18 PM UTC-7, Dave Nadler wrote:
> On Sunday, October 20, 2013 1:07:38 PM UTC-4, Darryl Ramm wrote:
>
> > Uh? Why are you talking about "thermal trips" and
>
> > automatic resetting?
>
>
>
> Hi Darryl - I think he's talking about PTCs, which are
>
> appropriate in some situations but not here...

Hi Dave - yes, hopefully common sense would prevent their use. And automatic resetting breakers are also forbidden by CFR 14 23.1357. But part 23 may not apply to a JAR-22 derived type certificate on a glider but its a good place to get input on ways to do things and what an A&P/DAR/FSDO would like to see. Folks really ought to think Klixon type breakers if using a breaker on gliders.

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.

Also see FAA AC 43.13 Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair. Chapter 11 (Electrical Systems). Lots of good stuff there that should be read by anybody who is considering messing around with any aircraft wiring, not all of it applies to gliders however. And as promoted before on r.a.s. there is lots of advice on aircraft wiring on this web site. http://www.aeroelectric.com/articles.html (mostly intended for home builders of power aircraft)

---

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.

The most important place for circuit breakers is right at the battery, typically a 5A or 10A breaker mounted on the battery or right next to it that will protect your aircraft/wiring harness from a fire caused by a dead short.. I would use a breaker for that, easy to reset, never missing a replacement fuse etc. and the voltage drop is relatively insignificant for these higher current breakers. That primary circuit protection is in JAR-22 but is unfortunately vague.

What you do downsteam for there is more complex, some avionics/device vendors will spec a slow or some cases fast blow fuse to protect delicate devices, some will say a breaker is OK. Read the documentation. Get advice from somebody experienced with this stuff who can look at exactly what you are doing. Note the FAR and JAR requirements for each "critical"/"saftey of flight" device to have its own separate overload protection, and just good common sense as well.

Darryl

[JohnDeRosa]

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

[[email protected]]

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-p1m1-5a/circuit-breaker-thermal-250v-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

[[email protected]]

Ū1jd6

[Muttley]

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.php?t=8160&highlight=zentraleinheit

[Bruno Ramseyer]

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 Marotta]

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

[[email protected]]

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.
>

[Muttley]

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=0B98QDGWDnrb1MzlISDl6am1tSU0

[Roy B.]

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

[[email protected]]

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.

[Eric Greenwell[_4_]]

> 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/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[OHM Ω]

Quote: "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-p1m1-5a/circuit-breaker-thermal-250v-5a/dp/98K5389"

Quote: "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."

MANY good comments in this entire thread. I don't like (glass) fuses. I do like Tyco W31 breaker(s)/switch(es) in my panel. See http://www.aircraftspruce.com/catalog/elpages/pbcircuitbrkr2.php?clickkey=5950.

More information here > http://aviation.derosaweb.net/presentations/

[SF]

I started to reply to this and then I noticed Hey, I'm the one that started it several years ago. Here is how this story ended up.

I installed a terminal strip with a inline bladed fuse on every terminal. One side of the terminal strip is a 12V bus. Every instrument hooks up to its own individual terminal. Have a large toggle (locking) switch to connect each battery to the 12V bus. Each device without it's own on off switch, has a small toggle (locking) ON/OFF switch on the panel. The only panel mounted fuse is for the (unswitched) gear horn circuit. just in case another of those dang magnetic switches falls off in flight again. 3 seasons on the new panel, no regrets or issues.

SF