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Z-19/RB Question

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mrspudandcompany(at)veriz
Guest

Posted: Sun Jul 27, 2008 9:45 am Post subject: Z-19/RB Question

Bob,  

   

In reviewing the Z-19/RB drawing, I have a question regarding the endurance bus feed.  There is a diode feed from the main bus, with which I have no problem. However, if the alternator fails and the low voltage module opens the engine battery contactor, there is no way to power the endurance bus from the engine battery.  In this case both paths to the endurance bus come from the main battery.  Did you intend for this wiring to be this way or should the EBUS ALT FEED connection be made to the engine battery bus instead of to the main battery bus?  

   

Roger  

       [quote][b]

nuckolls.bob(at)cox.net
Guest

Posted: Sun Jul 27, 2008 10:50 am Post subject: Z-19/RB Question

At 01:42 PM 7/27/2008 -0400, you wrote:



 	  Quote: 	
		  Bob,



In reviewing the Z-19/RB drawing, I have a question regarding the 

endurance bus feed.  There is a diode feed from the main bus, with which I 

have no problem. However, if the alternator fails and the low voltage 

module opens the engine battery contactor, there is no way to power the 

endurance bus from the engine battery.  In this case both paths to the 

endurance bus come from the main battery.  Did you intend for this wiring 

to be this way or should the EBUS ALT FEED connection be made to the 

engine battery bus instead of to the main battery bus?


	


   No, the normal feed is from the main bus which

   (in normal operations) is powered from the main

   bus supported by the alternator and two batteries.



   In case of alternator failure (and with the engine

   battery switch in the AUTO Mode), the engine battery

   is automatically separated off to support only

   the engine. The main battery is still supporting

   the main bus . . . until the pilot elects to drop

   to an endurance mode (main battery contactor OFF,

   alternate feedpath closed).



   Normally, you would never want to power the endurance

   bus from the engine battery unless you've suffered

   multiple-failures (main battery craps). Even then

   you're probably better off reverting to the J-3 mode

   with stuff from the flight bag as opposed to burdening

   the engine battery with keeping the fan running

   -AND- powering up stuff on the panel.



   So your observations are correct, there was never

   any intention of powering the e-bus from the engine

   battery.



   However, you ALWAYS have the option of closing both

   battery contactors and running the whole airplane

   from both batteries in parallel. The set of

   circumstances that would make this necessary/attractive

   are exceedingly rare. If it were my airplane, I'd

   have to be really hard pressed (and probably il-prepared)

   to burden the engine battery with more than running the

   engine.



   Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

mikefapex

Joined: 05 Jul 2007
Posts: 70
Location: Colorado

Posted: Sun Jul 27, 2008 2:40 pm Post subject: Re: Z-19/RB Question

Bob,



In normal operations of a Z-19, would you have the EBUS ALT FEED switch turned ON (closed)?  Seems that would keep the emergency switch manipulation to just one, the Master OFF.  The ENGINE BAT switch in the AUTO position would already disconnect the Engine Battery.

Do I have this right? Thanks,



Mike

nuckolls.bob(at)cox.net
Guest

Posted: Sun Jul 27, 2008 6:29 pm Post subject: Z-19/RB Question

At 03:40 PM 7/27/2008 -0700, you wrote:

 	  Quote: 	
		  



Bob,



In normal operations of a Z-19, would you have the EBUS ALT FEED switch 

turned ON (closed)?  Seems that would keep the emergency switch 

manipulation to just one, the Master OFF.  The ENGINE BAT switch in the 

AUTO position would already disconnect the Engine Battery.

Do I have this right? Thanks,


	


  You can if you wish. However, it's an ALTERNATE feed

  path and needs to be pre-flight tested. I'd turn

  it ON first thing and get the ATIS and clearance

  delivery. Then shut it OFF, start the engine, and leave

  it off until such time as needed to mitigate

  the effects of an alternator failure.



  Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

mikefapex

Joined: 05 Jul 2007
Posts: 70
Location: Colorado

Posted: Mon Jul 28, 2008 6:19 am Post subject: Re: Z-19/RB Question

Bob,



Understood, that EBus switch is ALTERNATE path to powering the EBus. And as you said, turn it on, check ATIS are all good preflight procedures to test this path. 



I just wanted to confirm that once you are started and the alternator is running smoothly, it would do no harm to leave the EBus switch turned on (closed) during normal operations.



Thanks,



Mike

nuckolls.bob(at)cox.net
Guest

Posted: Tue Jul 29, 2008 5:08 pm Post subject: Z-19/RB Question

At 07:19 AM 7/28/2008 -0700, you wrote:

 	  Quote: 	
		  



Bob,



Understood, that EBus switch is ALTERNATE path to powering the EBus. And 

as you said, turn it on, check ATIS are all good preflight procedures to 

test this path.



I just wanted to confirm that once you are started and the alternator is 

running smoothly, it would do no harm to leave the EBus switch turned on 

(closed) during normal operations.


	


    No harm at all. This part of the design philosophy. No

    mis-ositioning of switches places any part of the

    system at-risk for failure.



    Bob . . .

        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

bicyclop(at)pacbell.net
Guest

Posted: Wed Jul 30, 2008 9:43 pm Post subject: Z-19/RB Question

Mike,



That's exactly how I've operated our RV for years. My reasoning for 

doing so is that I only have to turn off one switch (the master) in case 

of alternator failure. I don't have to worry about turning on the alt 

feed before doing so to avoid rebooting stuff. In fact, when my 

alternator quit working on my way to British Columbia last spring, 

that's what I did. Flipped one switch and kept going. Had enough battery 

for an hour's flight, landing at a towered airport for gas, a start and 

departure and another 45 minutes of flight and still had enough in the 

battery for a start after replacing the alternator. I turned off stuff 

we didn't need, but kept the electronic ignition, transponder and GPS 

going. Turned on and used the Com when I needed to and didn't worry 

about maintenance till we stopped at our intended destination for the night.



I turn on the alternate feed, check atis while I'm inserting my ear 

canal headset to make sure I've got them in right then I turn on the 

master, start and operate normally. My voltmeter is on the E-Buss so, if 

I do turn the alt feed off, I'm reading a voltage somewhat lower than 

the actual charging voltage. I don't have to do any math to see what the 

alternator is up to.



Pax,



Ed Holyoke



mikef wrote:

 	  Quote: 	
		   



 Bob,



 Understood, that EBus switch is ALTERNATE path to powering the EBus. And as you said, turn it on, check ATIS are all good preflight procedures to test this path. 



 I just wanted to confirm that once you are started and the alternator is running smoothly, it would do no harm to leave the EBus switch turned on (closed) during normal operations.



 Thanks,



 Mike





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=195343#195343

mikefapex

Joined: 05 Jul 2007
Posts: 70
Location: Colorado

Posted: Thu Jul 31, 2008 6:14 am Post subject: Re: Z-19/RB Question

Thanks Ed,  That is a helpful confirmation of my understanding. I am building my preflight/postflight checklists for this new z-19 system. I too don't want things to go 'offline' if the alternator dies.

bicyclop(at)pacbell.net
Guest

Posted: Thu Jul 31, 2008 9:18 pm Post subject: Z-19/RB Question

Just one more thing, Mike. I periodically test the diode feeding the 

E-Buss by turning on the master only or turning off the E-buss switch 

first and making sure that the stuff on the E-buss is hot. I don't want 

the alternate feed switch to be the single point of failure.



Pax,



Ed Holyoke



mikef wrote:

 	  Quote: 	
		   



 Thanks Ed,  That is a helpful confirmation of my understanding. I am building my preflight/postflight checklists for this new z-19 system. I too don't want things to go 'offline' if the alternator dies.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=195860#195860

nuckolls.bob(at)cox.net
Guest

Posted: Fri Aug 01, 2008 5:08 am Post subject: Z-19/RB Question

At 10:09 PM 7/31/2008 -0700, you wrote:

 	  Quote: 	
		  



Just one more thing, Mike. I periodically test the diode feeding the 

E-Buss by turning on the master only or turning off the E-buss switch 

first and making sure that the stuff on the E-buss is hot. I don't want 

the alternate feed switch to be the single point of failure.


	


   The e-bus alternate feed switch cannot be a single point

   of e-bus failure since it's the second of two independent

   feed paths to the e-bus. If the alternate feed path is

   pre-flight tested and then "put away unless needed" then

   probability of it being available as needed is very high.



   This was the spirit and intent of the alternate feed path

   philosophy re-enforced by the notion that it was a good

   thing to shut battery contactors off during battery only

   operations.



   Bob . . .

nuckolls.bob(at)cox.net
Guest

Posted: Fri Aug 01, 2008 5:20 am Post subject: Z-19/RB Question

At 07:14 AM 7/31/2008 -0700, you wrote:

 	  Quote: 	
		  



Thanks Ed,  That is a helpful confirmation of my understanding. I am 

building my preflight/postflight checklists for this new z-19 system. I 

too don't want things to go 'offline' if the alternator dies.


	


   The only thing that happens when the alternator quits

   is that bus voltage drops from a nominal 14.2 volts down

   to about 12.6 volts. If you did NOTHING at this point in

   time, you would be no worse off than if you were flying

   a C-172 except that your options for load shedding

   for battery only ops are more limited in the C-172.



   If you were typical of C-172 drivers, you would have

   no idea how long the battery would carry the minimum

   loads you were able to achieve because not one C-172

   driver in 1000 has any first hand knowledge of (1)

   battery capacity and (2) how long his minimized loads

   will run from that capacity.



   If you did not have the alternate e-bus feeder

   installed (replace the diode with an avionics

   master switch) you MIGHT still have a leg up on a

   C-172 driver in that you could conduct the experiments

   to KNOW how much battery only endurance you had with

   that particular architecture.



   Now, having added the alternate feed path and the

   diode that prevents mis-routing of energy, you

   have an opportunity to craft a confident plan-b

   for dealing with alternator failure. The plan-b

   removes all loads not necessary for en route operation

   of the airplane . . . which can be quite small.

   This INCLUDES energies need to keep the battery

   contactor closed. Once you are cleared to land

   you can turn the battery master back ON and run

   any number of additional goodies you wish. Whether

   or not they continue to run to the parking spot

   is immaterial to the outcome of the flight.



   There is no compelling reason to fly with the alternate

   feed path closed. Even if your ships voltmeter feeds

   from the e-bus, it reads about .7v lower than

   main bus . . . so what? That value becomes the

   NORMAL operating point for the e-bus. The fact

   that it does not represent main bus voltage is

   of no consequence to you as a pilot in the operation

   of the airplane.



   Bob . . .



 	  Quote: 	
		  Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=195860#195860



Checked by AVG - http://www.avg.com

6:37 PM


	




        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

bicyclop(at)pacbell.net
Guest

Posted: Fri Aug 01, 2008 10:37 am Post subject: Z-19/RB Question

Bob,



What I was saying is that I use the "alternate feed switch" (labeled 

"E-Buss") as the primary feed to the E-buss, sort of like an avionics 

master, and that the diode on the master is now a backup and as such, I 

need to make sure it hasn't failed leaving only one feed path available 

to my essential equipment. I do test the feed path, but I don't put it 

away until needed, as you say, because I feel having it on simplifies 

the process of load shedding (including the contactor and alternator 

field) in case of alternator failure (or ground ops). I chose this 

method because I don't want to risk inflight  re-booting of my EFIS and 

autopilot by flipping switches in the wrong order. That I don't have to 

do (admittedly easy) math with the .7 volt diode drop is gravy, not the 

deciding factor.



It strikes me that, if one didn't mind having an extra switch, the diode 

could be eliminated as well, leaving the E-Buss as a separate entity 

from the main buss. The philosophy of having independent feed paths and 

being able to simply shed unnecessary loads would still be served.



Pax,



Ed Holyoke

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)cox.net>



 At 10:09 PM 7/31/2008 -0700, you wrote:

> 

> <bicyclop(at)pacbell.net>

>

> Just one more thing, Mike. I periodically test the diode feeding the 

> E-Buss by turning on the master only or turning off the E-buss switch 

> first and making sure that the stuff on the E-buss is hot. I don't 

> want the alternate feed switch to be the single point of failure.



   The e-bus alternate feed switch cannot be a single point

   of e-bus failure since it's the second of two independent

   feed paths to the e-bus. If the alternate feed path is

   pre-flight tested and then "put away unless needed" then

   probability of it being available as needed is very high.



   This was the spirit and intent of the alternate feed path

   philosophy re-enforced by the notion that it was a good

   thing to shut battery contactors off during battery only

   operations.



   Bob . . .

nuckolls.bob(at)cox.net
Guest

Posted: Fri Aug 01, 2008 12:50 pm Post subject: Z-19/RB Question

At 11:33 AM 8/1/2008 -0700, you wrote:

 	  Quote: 	
		  



Bob,



What I was saying is that I use the "alternate feed switch" (labeled 

"E-Buss") as the primary feed to the E-buss, sort of like an avionics 

master, and that the diode on the master is now a backup and as such, I 

need to make sure it hasn't failed leaving only one feed path available to 

my essential equipment. I do test the feed path, but I don't put it away 

until needed, as you say, because I feel having it on simplifies the 

process of load shedding (including the contactor and alternator field) in 

case of alternator failure (or ground ops). I chose this method because I 

don't want to risk inflight  re-booting of my EFIS and autopilot by 

flipping switches in the wrong order. That I don't have to do (admittedly 

easy) math with the .7 volt diode drop is gravy, not the deciding factor.



It strikes me that, if one didn't mind having an extra switch, the diode 

could be eliminated as well, leaving the E-Buss as a separate entity from 

the main buss. The philosophy of having independent feed paths and being 

able to simply shed unnecessary loads would still be served.


	


   The diode was considered necessary and useful to eliminate

   the potential for having both switches closed at the same time

   and having the main bus take power through the e-bus alternate

   feed path . . . a bonus of using the diode IS the automatic

   switching of one feed path and elimination of the switch.



   Of course, how you choose to modify the system and its

   operation is a personal decision.



   Bob . . .

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