Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Strobe power ground?

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

hotwheels

Joined: 01 Jun 2007
Posts: 240

Posted: Mon Feb 22, 2010 4:40 am Post subject: Strobe power ground?

I have a Wheelen strobe power pack in the back of an RV-10. My forest of tabs ground is on the firewall. Should I pull the power pack ground forward or just ground locally? I can't think of a good reason the strobe would be a ground loop victim.



Thanks in advance for your reply.



Jay

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Feb 22, 2010 6:47 am Post subject: Strobe power ground?

At 06:40 AM 2/22/2010, you wrote:

 	  Quote: 	
		  



I have a Wheelen strobe power pack in the back of an RV-10. My 

forest of tabs ground is on the firewall. Should I pull the power 

pack ground forward or just ground locally? I can't think of a good 

reason the strobe would be a ground loop victim.



Thanks in advance for your reply.


	


    See illustrations in Figure Z15.



    Bob . . .

johngoodman

Joined: 18 Sep 2006
Posts: 530
Location: GA

Posted: Mon Feb 22, 2010 11:32 am Post subject: Re: Strobe power ground?

I think that Bob is saying you can ground it to the airframe or the forest of tabs. It brings up another question concerning aluminum RVs. If the forest of tabs is on the stainless steel firewall and the engine is grounded to it, shouldn't the forest of tabs be linked to some nearby aluminum for better grounding?

I think a braided line has been suggested, but a wire back to the actual main battery ground would also work - but how big? A #2awg is impractical. Would somethings as small as a #10awg be good enough, since it's all still attached to the airframe?

John

_________________
#40572 Phase One complete in 2011

peter(at)sportingaero.com
Guest

Posted: Mon Feb 22, 2010 1:54 pm Post subject: Strobe power ground?

Let's think about what is going on here for a moment. The idea is to 

allow the current to flow back to the alternator/battery without much 

impediment (and without inducing ground loops in sensitive audio 

circuits). The firewall is riveted to the rest of the fuselage with 

perhaps hundreds of rivets, each clamping the components tightly 

together. The forest of tabs has a large brass nut on it to which the 

battery earth strap is connected. All the frames in the fuselage are 

riveted to the skin and the longerons with 10s of rivets. Installing an 

earth stud (that makes good contact with the metal) on a frame near to 

the strobe power supply, and hooking the power supply up to it with a 

#18 wire, will complete the circuit and achieve the desired aim with 

minimum weight. Sure you can run a #10 (or #1 wire back to the forest 

of tabs, but its completely redundant.



Peter



johngoodman wrote:

 	  Quote: 	
		   



 I think that Bob is saying you can ground it to the airframe or the forest of tabs. It brings up another question concerning aluminum RVs. If the forest of tabs is on the stainless steel firewall and the engine is grounded to it, shouldn't the forest of tabs be linked to some nearby aluminum for better grounding?

 I think a braided line has been suggested, but a wire back to the actual main battery ground would also work - but how big? A #2awg is impractical. Would somethings as small as a #10awg be good enough, since it's all still attached to the airframe?

 John



 --------

 #40572 QB. Engine on, wing attach coming soon. Panel delivery soon.

 N711JG reserved





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=287678#287678

johngoodman

Joined: 18 Sep 2006
Posts: 530
Location: GA

Posted: Mon Feb 22, 2010 3:18 pm Post subject: Re: Strobe power ground?

Peter is right, but I do think Bob suggested some kind of supplemental grounding if the forest of tabs is on the stainless steel firewall.

John

_________________
#40572 Phase One complete in 2011

MauleDriver(at)nc.rr.com
Guest

Posted: Mon Feb 22, 2010 4:00 pm Post subject: Strobe power ground?

I have no idea whether it is acceptable - but I have a #8 running from 

my batteries to the forest of tabs on the firewall with the thought that 

the tab is grounded to the airframe and directly.  Feel good about it 

and think I discussed it with Bob here sometime ago.



Bill



johngoodman wrote:

 	  Quote: 	
		   



 I think that Bob is saying you can ground it to the airframe or the forest of tabs. It brings up another question concerning aluminum RVs. If the forest of tabs is on the stainless steel firewall and the engine is grounded to it, shouldn't the forest of tabs be linked to some nearby aluminum for better grounding?

 I think a braided line has been suggested, but a wire back to the actual main battery ground would also work - but how big? A #2awg is impractical. Would somethings as small as a #10awg be good enough, since it's all still attached to the airframe?

 John



 --------

 #40572 QB. Engine on, wing attach coming soon. Panel delivery soon.

 N711JG reserved

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 23, 2010 8:28 am Post subject: Strobe power ground?

At 01:32 PM 2/22/2010, you wrote:

 	  Quote: 	
		  

<johngoodman(at)earthlink.net>



I think that Bob is saying you can ground it to the airframe or the 

forest of tabs. It brings up another question concerning aluminum 

RVs. If the forest of tabs is on the stainless steel firewall and 

the engine is grounded to it, shouldn't the forest of tabs be linked 

to some nearby aluminum for better grounding?


	


  Not necessary. The only currents carried on the firewall sheet

  are those few items locally grounded as shown on



http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z15K3p1.pdf



 	  Quote: 	
		  I think a braided line has been suggested, but a wire back to the 

actual main battery ground would also work - but how big? A #2awg is 

impractical. Would somethings as small as a #10awg be good enough, 

since it's all still attached to the airframe?


	


   No added value. If you do a micro-ohmmeter check between

   the firewall ground block and major aluminum airframe

   structure, it will be hundreds of micro-ohms.



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 23, 2010 8:31 am Post subject: Strobe power ground?

At 02:29 PM 2/22/2010, you wrote:

 	  Quote: 	
		  

<MauleDriver(at)nc.rr.com>



I have no idea whether it is acceptable - but I have a #8 running 

from my batteries to the forest of tabs on the firewall with the 

thought that the tab is grounded to the airframe and directly.  Feel 

good about it and think I discussed it with Bob here sometime ago.


	


   ???? Did I recommend this . . . or just offer that

   it didn't hurt anything ???



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 23, 2010 8:34 am Post subject: Strobe power ground?

At 05:18 PM 2/22/2010, you wrote:

 	  Quote: 	
		  

<johngoodman(at)earthlink.net>



Peter is right, but I do think Bob suggested some kind of 

supplemental grounding if the forest of tabs is on the stainless 

steel firewall.


	


   Hmmmm . . . I'll need to search the archives on that.

   I wonder if I was smoking something really good that

   night. I can't imagine the thought processes that

   would have made a redundant ground attractive.



   I do seem to recall some folks wondering if they could

   ground tail mounted batteries locally . . . or does

   the system work better if battery ground is brought

   forward on it's own wire.



   Upon further reflection, we've been grounding batteries

   in the tail on metal airplanes for a very long time.

   Tradeoffs for performance are pretty small if even

   measurable.



   Bob . . .

MauleDriver(at)nc.rr.com
Guest

Posted: Tue Feb 23, 2010 11:15 am Post subject: Strobe power ground?

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 02:29 PM 2/22/2010, you wrote:

> 

> <MauleDriver(at)nc.rr.com>

>

> I have no idea whether it is acceptable - but I have a #8 running 

> from my batteries to the forest of tabs on the firewall with the 

> thought that the tab is grounded to the airframe and directly.  Feel 

> good about it and think I discussed it with Bob here sometime ago.



   ???? Did I recommend this . . . or just offer that

   it didn't hurt anything ???



   Bob . . .



You definitely didn't recommend it and from what I can see didn't even 
	


offer a comment.  My bad in suggesting you did.

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 23, 2010 7:50 pm Post subject: Strobe power ground?

 	  Quote: 	
		  >   ???? Did I recommend this . . . or just offer that

>   it didn't hurt anything ???

You definitely didn't recommend it and from what I can

see didn't even offer a comment.  My bad in suggesting you did.


	


   No problem. With as many conversations as I participate

   in on-list, off-list and with clients, it's difficult

   to recall sometimes just who said what to whom and

   why. That's the nice thing about archives. I've got every

   document I ever posted to the List on file. It's

   been handy on many occasions over the years.



   Bob . . .

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum