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

Z-14 Switch Combos

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

Phil.Perry(at)netapp.com
Guest

Posted: Sat Jan 02, 2010 7:10 pm Post subject: Z-14 Switch Combos

I’m getting a handle on Z-14 from an operational perspective and have a couple of questions about the switch combinations that could create issues.  

   

Obviously with the added complexity of managing two batteries, two alternators, and a cross feed can create some interesting combinations.  

   

Are there any combo’s that we should be aware of that would create over voltage or any other scenarios of concern?   

   

In the event of a failure (for example Alt 2 failure), is there a specific order for shutting off the  bad alt and then enabling the cross feed?  

   

Thanks,  

Phil  

   

   

      [quote][b]

bcondrey

Joined: 03 Apr 2006
Posts: 580

Posted: Mon Jan 04, 2010 8:00 am Post subject: Re: Z-14 Switch Combos

Phil,



There isn't anything bad that will happen regardless of switch positions for Z-14 as depicted in the stock diagrams.  You've got 2 bus power switches and either can be on or off irrespective of the other (they are isolated).  Further, the x-feed switch can be on even if both alternators are online with no ill effect (at least with B&C externally regulated devices).  



Bob

RV-10 N442PM (flying with Z-14)

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jan 04, 2010 9:45 am Post subject: Z-14 Switch Combos

At 10:00 AM 1/4/2010, you wrote:

 	  Quote: 	
		  

<bob.condrey(at)baesystems.com>



Phil,



There isn't anything bad that will happen regardless of switch 

positions for Z-14 as depicted in the stock diagrams.  You've got 2 

bus power switches and either can be on or off irrespective of the 

other (they are isolated).  Further, the x-feed switch can be on 

even if both alternators are online with no ill effect (at least 

with B&C externally regulated devices).


	


   There are no "gotchas" lurking in the design

   or operation of Figure Z-14 . . . nothing is

   at risk for damage due to mis-positioning of

   switches.



   Bob . . .

MauleDriver(at)nc.rr.com
Guest

Posted: Mon Jan 04, 2010 11:28 am Post subject: Z-14 Switch Combos

Phil, that's been my understanding too but I have no actual experience.  

Bob C. here knows what he's talking about.



Bill



bcondrey wrote:

 	  Quote: 	
		   



 Phil,



 There isn't anything bad that will happen regardless of switch positions for Z-14 as depicted in the stock diagrams.  You've got 2 bus power switches and either can be on or off irrespective of the other (they are isolated).  Further, the x-feed switch can be on even if both alternators are online with no ill effect (at least with B&C externally regulated devices).  



 Bob

 RV-10 N442PM (flying with Z-14)





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 80027#280027

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jan 04, 2010 12:09 pm Post subject: Z-14 Switch Combos

At 09:08 PM 1/2/2010, you wrote:

 	  Quote: 	
		  I'm getting a handle on Z-14 from an operational perspective and 

have a couple of questions about the switch combinations that could 

create issues.



Obviously with the added complexity of managing two batteries, two 

alternators, and a cross feed can create some interesting combinations.



Are there any combo's that we should be aware of that would create 

over voltage or any other scenarios of concern?



In the event of a failure (for example Alt 2 failure), is there a 

specific order for shutting off the  bad alt and then enabling the cross feed?


	


   No . . . there's no risks for any 'mis management' of

   switches. But you may not close the cross-feed ever.



   Depending on what YOU power from each of the two busses,

   how YOU use the airplane and which alternator quit, you

   need to re-configure the system to maximize probablity

   of a no sweat arrival at airport of intended destination.

   This MIGHT call for immediate closure of the cross-feed

   (but probably not). Or it might remain open with one

   bus shut down completely until airport is in sight.



   Z-14 is just a fancier version of Z-13/8 which is a

   fancier version of Z-11 with an E-bus.  The level

   of fanciness only drives your decisions on best

   utilization of limited resources for engine driven

   power. That procedure is something that you have

   to develop.



   Bob . . .

Phil.Perry(at)netapp.com
Guest

Posted: Mon Jan 04, 2010 6:45 pm Post subject: Z-14 Switch Combos

So we were on a good path until, "But you may not close the cross-feed

ever."



If that's the case, what good is the cross-feed if the switch is off

limits???  I think your intentions were to say only in an emergency when

it is required?



Let's looks a scenario where I forget to open the cross-feed after

start.  The other two contactors for the Alt/Batt are closed too.  What

are the effects of the electrical system for prolonged cross-feed

closure on a cross country tour across the southern states?  Any battery

damage?



My guess is that the alternators would be shedding load back and forth

for the flight and never stabilize.



I think I'm getting closer to understanding it.  I just want to make

sure I understand everything operationally before I dedicate myself to a

specific diagram only to be disappointed later.



Thanks again for your help,

Phil



--

william_slaughter(at)att.
Guest

Posted: Mon Jan 04, 2010 7:43 pm Post subject: Z-14 Switch Combos

I believe that "may not..." should be translated as "may never have occasion

to", rather than "you must not do that". At least that's the way I read it.



William



--

n8zg(at)mchsi.com
Guest

Posted: Mon Jan 04, 2010 7:49 pm Post subject: Z-14 Switch Combos

Phil - 



I think you misinterpreted Bob's comment.  It appears you read it to say

"you're never ALLOWED to close the cross-feed switch", when Bob meant "you

might not ever have a reason to close it". 



Neal




<Phil.Perry(at)netapp.com>



So we were on a good path until, "But you may not close the cross-feed

ever."



If that's the case, what good is the cross-feed if the switch is off

limits???  I think your intentions were to say only in an emergency when

it is required?



Phil

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Mon Jan 04, 2010 8:13 pm Post subject: Z-14 Switch Combos

Phil and William;



My reading of the statement agrees with William's translation as well.



Bob McC



[quote] --

_________________
Bob McC
Falco #908
(just starting)

Phil.Perry(at)netapp.com
Guest

Posted: Mon Jan 04, 2010 9:02 pm Post subject: Z-14 Switch Combos

Awesome..  I get it now..



Thanks for the help and clarification...



Phil

--

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jan 05, 2010 7:29 am Post subject: Z-14 Switch Combos

At 09:08 PM 1/4/2010, you wrote:

 	  Quote: 	
		  



Phil -



I think you misinterpreted Bob's comment.  It appears you read it to say

"you're never ALLOWED to close the cross-feed switch", when Bob meant "you

might not ever have a reason to close it".



Neal


	


   Correct. The process for deciding how to operate

   Z-14 is dependent upon what devices are

   fed from each bus and how you use the airplane.

   Z-14 was originally crafted for a guy building

   a Glasair with full up IFR capability in both

   seats. Further, it was the builder's intent to

   use this machine in missions that most of us

   work hard to avoid.



   Z-14 offers OPTIONS for deciding how you will

   manage energy resources that have become limited

   due to failure of some component like an alternator

   or battery contactor.



   There is no SET PROCEDURE I can offer you without

   doing the same failure modes effects analysis

   I would conduct for a TC aircraft with a similar

   system installed and tailored to the most demanding

   mission for which the airplane is outfitted.



   Z-14's cross-feed contactor solved a problem

   with attempting to PARALLEL two alternators

   in a dual alternator airplane by making them

   responsible for SEPARATE systems in normal

   operations.



   Z-13/8 was crafted to take exploit the existence

   of an unused engine accessory drive pad when

   a vacuum pump is removed. Some politicians hate

   to waste a good crisis, I had to waste a good

   drive pad. When considered against the quantum

   jumps in reliability offered by modern alternators

   and artfully maintained RG batteries, I believe

   Z-13/8 is about the most elegant solution to

   powering up the light airplane for 99 plus

   percent of all OBAM aircraft.



   If you have Z-14 installed, then share with us

   how equipment in your airplane is powered from

   the two busses along with your vision of how

   you expect to use this airplane. Is it important

   to you to forestall a dark-n-stormy night story

   'cause you've had an alternator go belly up while

   night IFR over the Rockies crossing a weather

   front? If so, what items of equipment are installed

   and how are they spread between the two systems?



   Bob . . .

Phil.Perry(at)netapp.com
Guest

Posted: Wed Jan 06, 2010 8:24 am Post subject: Z-14 Switch Combos

Hey Bob,



It looks like the crossfeed switch doubles as a starter switch in your

diagram, is that correct?



I'm planning on going with a push button to start, so I'll probably

modify the setup slightly.  But just want to make sure I'm reading it

correctly.



Thanks,

Phil



--

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Jan 06, 2010 8:33 am Post subject: Z-14 Switch Combos

At 10:19 AM 1/6/2010, you wrote:

 	  Quote: 	
		  



Hey Bob,



It looks like the crossfeed switch doubles as a starter switch in your

diagram, is that correct?


	


   Yes . . . it's spring loaded out of the start position.

   It offers automatic closure of the cross-feed contactor

   during start.

 	  Quote: 	
		  I'm planning on going with a push button to start, so I'll probably

modify the setup slightly.  But just want to make sure I'm reading it

correctly.


	


   Then the cross-feed switch can be SPST.



   Bob . . .

Phil.Perry(at)netapp.com
Guest

Posted: Wed Jan 06, 2010 8:07 pm Post subject: Z-14 Switch Combos

Thanks Bob...



I'll make it a DPDT and use the second pole for a nag-light indicating

the x-feed switch is closed.



Great design.  Thanks for saving us a bunch of work.



Phil

--

klehman(at)albedo.net
Guest

Posted: Thu Jan 07, 2010 5:24 am Post subject: Z-14 Switch Combos

Phil

Even better than a double pole switch might be staying with the SPST 

switch and wiring the light to actually show when the crossfeed 

contactor is activated. If you implement auto paralleling during 

cranking, in addition to showing when the switch is active, the light 

will then also confirm auto paralleling. If the engine ever cranks 

slowly, you will immediately know whether the crossfeed contactor is 

being commanded to close.

Ken



Perry, Phil wrote:

 	  Quote: 	
		   

 

 Thanks Bob...

 

 I'll make it a DPDT and use the second pole for a nag-light indicating

 the x-feed switch is closed.

 

 Great design.  Thanks for saving us a bunch of work.

 

 Phil

 



> Hey Bob,

>

> It looks like the crossfeed switch doubles as a starter switch in your

> diagram, is that correct?

 

    Yes . . . it's spring loaded out of the start position.

    It offers automatic closure of the cross-feed contactor

    during start.

 

 

> I'm planning on going with a push button to start, so I'll probably

> modify the setup slightly.  But just want to make sure I'm reading it

> correctly.

 

    Then the cross-feed switch can be SPST.

 

    Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Jan 07, 2010 5:37 am Post subject: Z-14 Switch Combos

At 09:58 PM 1/6/2010, you wrote:

 	  Quote: 	
		  



Thanks Bob...



I'll make it a DPDT and use the second pole for a nag-light indicating

the x-feed switch is closed.


	


    You can wire a lamp across the contactor coil to

    do that. Consider an LED indicator with resistors

    in BOTH leads located right at the contactor. This

    eliminates the need to fuse the wires.

 	  Quote: 	
		  Great design.  Thanks for saving us a bunch of work.


	


    You're welcome.



    Bob . . .

Phil.Perry(at)netapp.com
Guest

Posted: Thu Jan 07, 2010 11:36 am Post subject: Z-14 Switch Combos

I think I'll have to fuse them anyway.  The wire run length from the

contactor to the panel is pretty lengthy and I'd feel better about

putting a fuse inline.



What's the purpose of the resistors?    Is that to encourage the

electrons to flow through the coil instead of the LED?



Phil



--

william_slaughter(at)att.
Guest

Posted: Thu Jan 07, 2010 3:59 pm Post subject: Z-14 Switch Combos

LED's run on about 2-3 volts. The resistors provide voltage drop.



William



--

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jan 08, 2010 3:25 pm Post subject: Z-14 Switch Combos

At 01:25 PM 1/7/2010, you wrote:

 	  Quote: 	
		  



I think I'll have to fuse them anyway.  The wire run length from the

contactor to the panel is pretty lengthy and I'd feel better about

putting a fuse inline.



What's the purpose of the resistors?    Is that to encourage the

electrons to flow through the coil instead of the LED?


	


   Fuses protect wires . . . but so do the resistors. If your

   led calls for say 1000 ohms total resistance in series

   to achieve desired brightness, then consider two

   510 ohm resistors in series with each lead right

   at the contactor. See:



http://www.aeroelectric.com/articles/Homeless/Homeless_Components.htm



   The idea is that the resistors (1) take care of

   LED requirements and (2) shorting either lead to

   the airframe doesn't create a hazard because the

   resistors limit the current.



   We did a similar thing with the alternator diagnosis

   feature of our now discontinued AEC9021 voltmeter/

   loadmeter:



http://www.aeroelectric.com/Catalog/AEC/9021/9021-704F.pdf



   On pages 6 and 9 you see a 470 ohm resistor tapping

   a sample of alternator field voltage. The resistor's

   presence is not detrimental to the diagnostic procedure

   described on page 2 but eliminates the need for a fuse

   by preventing alternator upset if the diagnostic wire becomes

   faulted.



   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