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  #51  
Old 01-27-2020, 12:24 PM
49clipper 49clipper is offline
 
Join Date: Dec 2006
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Default 49clipper

How does one wire the ignition on/off switches for pmags to allow to check to see if the internal alternator is working? 4 toggles or?
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  #52  
Old 01-27-2020, 12:31 PM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by 49clipper View Post
How does one wire the ignition on/off switches for pmags to allow to check to see if the internal alternator is working? 4 toggles or?
The simple way is to open the pMag breaker for this test. So just one control toggle for each pMag, and of course one breaker for each pMag.

Carl
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  #53  
Old 01-27-2020, 12:34 PM
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bkervaski bkervaski is offline
 
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Location: Birmingham, Alabama
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Quote:
Originally Posted by 49clipper View Post
How does one wire the ignition on/off switches for pmags to allow to check to see if the internal alternator is working? 4 toggles or?
Not by number of toggles of any switch ...

The PMAG internal generators work when engine is at 800rpm or higher.

If you set your engine to 1000rpm and remove power via a switch or breaker from the PMAG, they will continue running, confirming the generators are working.

I do this check just about every flight, one at a time.

Edit: Another confirmation that you're wired up correctly would be to set your engine to less than 750rpm and then remove the power from the PMAGs, the engine should stop.
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Last edited by bkervaski : 01-27-2020 at 12:46 PM.
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  #54  
Old 01-27-2020, 12:53 PM
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bkervaski bkervaski is offline
 
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Oh, I may have misunderstood your question, my bad. It seems you may have been asking what types of switches to wire up and not how to test.

Most people either use a breaker if PMAGs are installed after the fact and they don't want to modify the panel.

New builds I see a lot of folks using 3-position with the test position momentary:

https://www.steinair.com/product/s700-2-50-switch/

If you ask Brad at Emagair I think he recommends having 4 completely separate switches as I understand this setup makes it a bit easier to set initial timing.
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Last edited by bkervaski : 01-27-2020 at 12:57 PM.
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  #55  
Old 01-27-2020, 04:34 PM
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rv8ch rv8ch is offline
 
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Default pmag wiring

Quote:
Originally Posted by 49clipper View Post
How does one wire the ignition on/off switches for pmags to allow to check to see if the internal alternator is working? 4 toggles or?
Here's how I did it.



The "source" for my wiring diagrams is here:

http://www.rv8.ch/files/RV-8-HB-YMM-Wiring.drawio

You might have guessed from the filename that I used https://draw.io/ for the drawings.
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Last edited by rv8ch : 01-29-2020 at 10:52 AM. Reason: updated ground in diagram
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  #56  
Old 01-29-2020, 07:18 AM
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derLuigi derLuigi is offline
 
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Quote:
Originally Posted by rv8ch View Post
Here's how I did it.


edit: this post refers to an earlier version of the diagram, fixed now (see post #58)

Mickey,

I'm a bit confused by your wiring of pin 4 (the pin formerly known as p-lead). In flight the switch is in the upper position, right?
I might have a serious brainfart here but doesn't pin 4 behave the traditional way (grounded means the ignition is off - aka "kill-switch")?
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Last edited by derLuigi : 01-30-2020 at 05:39 AM.
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  #57  
Old 01-29-2020, 10:20 AM
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WingnutWick WingnutWick is offline
 
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So recently I had to re-install one of my PMags and I previously had the jumper out and EICAD advance shift -1.4 with max advance at 36 because jumper in was yielding way too hot CHTs even manually clicked back. I decided to try again the manual, jumper in, clocking -1.4 on this one I was reinstalling as I was told that you get the same thing as if you did it through the EICAD program and sure enough, CHTs are back to being very high! I?m not sure why there is a difference there but doing the 0-360 recommended EICAD -1.4 and 36 seems to agree a lot more with my motor than manually clocking -1.4 via the flywheel timing.

Also, correct me if I?m wrong but 1.4 isn?t a magic number when it comes manual clocking, it?s more ballpark. I think 1.4 came along because the software bit increments when using through EICAD are in 1.4 segments and 1.4 is more appropriate than -2.8. But manually clocking -2 degrees may in fact be the magic number (for example).
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  #58  
Old 01-29-2020, 10:25 AM
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rv8ch rv8ch is offline
 
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Default error in diagram

Quote:
Originally Posted by derLuigi View Post
Mickey,

I'm a bit confused by your wiring of pin 4 (the pin formerly known as p-lead). In flight the switch is in the upper position, right?
I might have a serious brainfart here but doesn't pin 4 behave the traditional way (grounded means the ignition is off - aka "kill-switch")?
Amazing - you are right - my diagram is wrong. Fixed. Thanks for catching this.
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Last edited by rv8ch : 01-29-2020 at 10:56 AM.
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  #59  
Old 01-29-2020, 11:22 AM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by WingnutWick View Post
So recently I had to re-install one of my PMags and I previously had the jumper out and EICAD advance shift -1.4 with max advance at 36 because jumper in was yielding way too hot CHTs even manually clicked back. I decided to try again the manual, jumper in, clocking -1.4 on this one I was reinstalling as I was told that you get the same thing as if you did it through the EICAD program and sure enough, CHTs are back to being very high! I?m not sure why there is a difference there but doing the 0-360 recommended EICAD -1.4 and 36 seems to agree a lot more with my motor than manually clocking -1.4 via the flywheel timing.

Also, correct me if I?m wrong but 1.4 isn?t a magic number when it comes manual clocking, it?s more ballpark. I think 1.4 came along because the software bit increments when using through EICAD are in 1.4 segments and 1.4 is more appropriate than -2.8. But manually clocking -2 degrees may in fact be the magic number (for example).
What are the CHTs?

Perhaps a base test would resolve this. For both pMags back out the EICAD shift (as in put the pMag back to stock). Time the engine per the installation instructions (TDC for a parallel valve or 5 degrees ATDC for an angle valve engine), pMag with jumper in.

See if that solves your issue.

Carl
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  #60  
Old 01-29-2020, 09:38 PM
keitht keitht is offline
 
Join Date: Jun 2016
Location: coupeville wa
Posts: 175
Default Pmag wiring

Quote:
Originally Posted by rv8ch View Post
Amazing - you are right - my diagram is wrong. Fixed. Thanks for catching this.
Couple of thoughts.
1. Turning the prop with pmags will result in a a full energy spark if there is any chance of a pmag being active. So having two switches - the kill switch and the power switch as separate switches for each pmag and having each power switch as a lighted switch may be a way to have a safer system.
2. Powering each backup Pmag power from the endurance bus through separated circuit breakers and switches allows a simpler more direct mag check during pre- takeoff checks. Run up to 1700 rpm Switch one kill switch then switch off the opposite pmag power. Repeat for the others pmag. Retard throttle to below 800 and switch off backup power to each pmag in turn and observe rpm drop.
Having the master power switch on while working on the plane, having a failed kill switch and turning the prop ( even slowly) could be a killer if a pmag is inadvertently powered.

KT
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