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Z13/8 VS Z12

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donvansanten(at)gmail.com
Guest

Posted: Tue Aug 15, 2017 4:00 pm Post subject: Z13/8 VS Z12

Listers,

Roughly eight months ago I asked a question relating to the Z12 diagram. I stated that I have Z13/8 system and was considering changing to the Z12 to take advantage of the additional power that the SD20 alternator offers. 

Bob responded that he would not recommend this as the Z13/8 offers more levels of protection. I decided to try to add the added layers of protection to the Z12.Battery 



I am using two PMAGS, the second edition versions that are powered by their internal alternators as long as the engine rpm remains above 700. 



My dual EFIS system uses the TCW backup battery system. The backup functions as a third power source for the EFIS system. More importantly it acts as a brown out battery to avoid EFIS rebooting which would cause me to have no oil pressure information immediately after engine start.

In the end I decided to build the Z12 without the E Bus or the Battery Bus. I would like to know what failure modes the Z13/8 would handle that the Z12 as described would not.

Thanks in advance for the information as well as any constructive   

criticism.

Don

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user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Tue Aug 15, 2017 7:15 pm Post subject: Re: Z13/8 VS Z12

I do not know the answer to your question, but I see nothing wrong with your plan, which is how many aircraft are wired except with the addition of a second alternator.

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_________________
Joe Gores

rick(at)beebe.org
Guest

Posted: Wed Aug 16, 2017 7:56 am Post subject: Z13/8 VS Z12

A timely question for me. I have a 2001 GlaStar that is about to get a 

glass panel upgrade. I bought a B&C BD410-H alternator to replace the 

vacuum pump. Since I believe that would easily be able to power the 

entire plane and I don't have an engine with electronic ignition I was 

leaning toward Z12 with no endurance bus. However I've also been 

studying Z13 to see if it makes more sense. I'm open to opinions on what 

to do in this relatively green-field application.



--Rick



On 8/15/2017 4:59 PM, don van santen wrote:

 	  Quote: 	
		   Listers,

 

 Roughly eight months ago I asked a question relating to the Z12 diagram. 

 I stated that I have Z13/8 system and was considering changing to the 

 Z12 to take advantage of the additional power that the SD20 alternator 

 offers.

 

 Bob responded that he would not recommend this as the Z13/8 offers more 

 levels of protection. I decided to try to add the added layers of 

 protection to the Z12.Battery

 I am using two PMAGS, the second edition versions that are powered by 

 their internal alternators as long as the engine rpm remains above 700.

 My dual EFIS system uses the TCW backup battery system. The backup 

 functions as a third power source for the EFIS system. More importantly 

 it acts as a brown out battery to avoid EFIS rebooting which would cause 

 me to have no oil pressure information immediately after engine start.

 

 In the end I decided to build the Z12 without the E Bus or the Battery 

 Bus. I would like to know what failure modes the Z13/8 would handle that 

 the Z12 as described would not.

 

 Thanks in advance for the information as well as any constructive

 

 criticism.

 

 Don

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nuckolls.bob(at)aeroelect
Guest

Posted: Thu Aug 17, 2017 8:28 am Post subject: Z13/8 VS Z12

At 06:59 PM 8/15/2017, you wrote:

  	  Quote: 	
		  Listers,



 Roughly eight months ago I asked a question relating to the Z12 diagram. I stated that I have Z13/8 system and was considering changing to the Z12 to take advantage of the additional power that the SD20 alternator offers. 



 Bob responded that he would not recommend this as the Z13/8 offers more levels of protection. I decided to try to add the added layers of protection to the Z12.Battery 	


    I'm trying to recall the context of that recommendation . . .

    but let's pretend like it didn't happen and start from

    scratch . . .



    I am especially fond of Z13/8 because it offers the lowest

    cost, lightest weight, failure tolerant architecture

    that exploits the oft-ignored vacuum pump drive pad

    on aircraft engines.



    Like ALL constellations of hardware, Z13/8 is not without

    limits. The major feature being the limits of an SD8 alternator

    to carry anticipated endurance loads.



  	  Quote: 	
		  I am using two PMAGS, the second edition versions that are powered by their internal alternators as long as the engine rpm remains above 700. My dual EFIS system uses the TCW backup battery system. The backup functions as a third power source for the EFIS system. More importantly it acts as a brown out battery to avoid EFIS rebooting which would cause me to have no oil pressure information immediately after engine start.



 In the end I decided to build the Z12 without the E Bus or the Battery Bus. I would like to know what failure modes the Z13/8 would handle that the Z12 as described would not. 	


   Z12 is a derivative of a band-aid pasted

   onto the architecture of TC aircraft that

   left the factory with one battery and one

   alternator. It too depends on the availability

   of a AND20000 drive pad turning at some useful

   RPM.



   The only difference is the AeroElectric addition

   of an E-bus.



   The obvious advantage of Z12 over Z13/8 is the greater

   support for endurance loads. Unlike Z13/8 + Ebus

   combination even allows you to eliminate battery

   contactor current from endurance loads. Extra

   snort available from the SD20 makes contactor load

   insignificant in the endurance equation. 



  	  Quote: 	
		  Thanks in advance for the information as well as any constructive 	


   In my mind, the major driver for upgrading to Z12

   is the size of your endurance loads. Just how

   much 'stuff' needs to stay lit up during the

   EN ROUTE phase of a flight that cannot be

   carried by an SD8?



   Recall that the first goal for adding a second alternator

   is to conserve stored energy in the battery for descent,

   approach and landing phase. Once you have the

   airport in sight, you should be able to run a whole

   panel of electro-whizzies with the battery making

   up the difference.



   What does your load analysis dictate? Is there no

   comfortable way you can sustain en route flight

   on an 8-10A endurance budget?



   If not, then Z12 is the next step up . . . a

   decision that totally unrelated to my personal

   fondness for any other architecture. 



 

   Bob . . .

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donvansanten(at)gmail.com
Guest

Posted: Thu Aug 17, 2017 1:31 pm Post subject: Z13/8 VS Z12

Bob,

Thanks for the reply.

There are many things that I find important when picking an electrical

architecture. In addition to cost, weight and failure tolerance. The

normal mission for the aircraft is more a deciding point than cost or

weight. Failure tolerance is vital.

I fly in and around four different class B air spaces. Twenty percent

of the flights involve IFR conditions anywhere from departing and

approaches only to four plus hours in hard IMC.

The cost difference is roughly $330. This is less than the cost of two fill ups.

The weight difference is roughly 3 pounds.

Therefore I will loose the 20 pounds that I put on while recovering

from an injury. I know that there would still be three extra pounds on

board, but I can live with the very slight extra cost of dragging the

extra weight around.



Now to what i consider the most important point which is failure tolerance.

After you recommended not switching from the Z13/8 to the Z20 I spent

a great deal of time/energy trying to make the Z20 as failure tolerant

as the Z13/8. I was able  to find one possible area of concern,

It is my belief based only on my experience that most primary

alternator failures are the result of belt drive failures. Most FBO's

only change the belt when it breaks. I do not know any experimental

owner that routinely changes out the belt.



So if a Z20 system looses its battery for and reason as per Joe Gores,

nothing happens as the primary alternator is already running. If

during the same flight the alternator belt breaks does the secondary

come on line?

It seems to me that the bus voltage would go to zero immediately. As

the SB voltage regulator needs voltage to provide field current to

make the SD20 run I think the SD20 would not come online. (If this is

incorrect please inform me.)

If the above is correct I came up with two solutions. One is to wire

one of the TCW standby battery leads to my E BUS switch which is not

currently connected to anything and the switch to the bus connector on

the  SB regulator to provide voltage until the SD20 comes online.

After that the E BUS switch would be opened.

The other option added cost and weight so it was abandoned. It was to

add an Odyssey PC310 battery switched through a 40 amp relay to the

main bus. This system would always be off during start.

Sorry for being so wordy. Do you see any serious problems with this

design excepting the possibly misunderstanding of the SB regulator

behavior under the described conditions.

Thanks again.

On Thu, Aug 17, 2017 at 9:27 AM, Robert L. Nuckolls, III

<nuckolls.bob(at)aeroelectric.com> wrote:

 	  Quote: 	
		   At 06:59 PM 8/15/2017, you wrote:



 Listers,



 Roughly eight months ago I asked a question relating to the Z12 diagram. I

 stated that I have Z13/8 system and was considering changing to the Z12 to

 take advantage of the additional power that the SD20 alternator offers.



 Bob responded that he would not recommend this as the Z13/8 offers more

 levels of protection. I decided to try to add the added layers of protection

 to the Z12.Battery

    I'm trying to recall the context of that recommendation . . .

    but let's pretend like it didn't happen and start from

    scratch . . .



    I am especially fond of Z13/8 because it offers the lowest

    cost, lightest weight, failure tolerant architecture

    that exploits the oft-ignored vacuum pump drive pad

    on aircraft engines.



    Like ALL constellations of hardware, Z13/8 is not without

    limits. The major feature being the limits of an SD8 alternator

    to carry anticipated endurance loads.



 I am using two PMAGS, the second edition versions that are powered by their

 internal alternators as long as the engine rpm remains above 700. My dual

 EFIS system uses the TCW backup battery system. The backup functions as a

 third power source for the EFIS system. More importantly it acts as a brown

 out battery to avoid EFIS rebooting which would cause me to have no oil

 pressure information immediately after engine start.



 In the end I decided to build the Z12 without the E Bus or the Battery Bus.

 I would like to know what failure modes the Z13/8 would handle that the Z12

 as described would not.

   Z12 is a derivative of a band-aid pasted

   onto the architecture of TC aircraft that

   left the factory with one battery and one

   alternator. It too depends on the availability

   of a AND20000 drive pad turning at some useful

   RPM.



   The only difference is the AeroElectric addition

   of an E-bus.



   The obvious advantage of Z12 over Z13/8 is the greater

   support for endurance loads. Unlike Z13/8 + Ebus

   combination even allows you to eliminate battery

   contactor current from endurance loads. Extra

   snort available from the SD20 makes contactor load

   insignificant in the endurance equation.



 Thanks in advance for the information as well as any constructive

   In my mind, the major driver for upgrading to Z12

   is the size of your endurance loads. Just how

   much 'stuff' needs to stay lit up during the

   EN ROUTE phase of a flight that cannot be

   carried by an SD8?



   Recall that the first goal for adding a second alternator

   is to conserve stored energy in the battery for descent,

   approach and landing phase. Once you have the

   airport in sight, you should be able to run a whole

   panel of electro-whizzies with the battery making

   up the difference.



   What does your load analysis dictate? Is there no

   comfortable way you can sustain en route flight

   on an 8-10A endurance budget?



   If not, then Z12 is the next step up . . . a

   decision that totally unrelated to my personal

   fondness for any other architecture.



   Bob . . .

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user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Thu Aug 17, 2017 4:44 pm Post subject: Re: Z13/8 VS Z12

Don,

It is highly unlikely that two failures will occur on the same flight: battery contactor and alternator belt, especially since battery contactors rarely fail.  But let's suppose it happens.  Assume the voltage regulator for the main alternator is set at 14.4 and the voltage regulator for the smaller alternator is set at 13.5 volts.  Both alternators are on-line when the failure occurs, but only the main alternator has been supplying power to the aircraft because its output voltage is higher.  The smaller alternator has been producing voltage but no current. 

 When the alternator belt breaks, the system voltage will not immediately drop to zero.  It will take time for the alternator to slow down and stop.  Let's say it takes 0.5 seconds.  During that brief time, the system voltage will fall.  When it gets to 13.5 volts, the smaller alternator will start pushing current because the higher voltage from the main alternator is no longer impeding it.   The smaller alternator should now supply the aircraft power, even with the battery disconnected.  At least that is my theory.  It needs to be confirmed with testing or refuted by Bob.

 If concerned about battery contactor failure, a 40 amp relay could be connected in parallel with it (disabled during engine cranking).

 A concern that I have is activation of the over-voltage protection device.  Will it disable both alternators?  If so, which is the greater danger, an actual over voltage condition, or the loss of both charging systems?  Perhaps the over-voltage set-point for main alternator could be one or two volts less than the set-point for the smaller alternator.

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_________________
Joe Gores

donvansanten(at)gmail.com
Guest

Posted: Thu Aug 17, 2017 5:22 pm Post subject: Z13/8 VS Z12

Thanks Joe,

That is what I expected/hoped for. The additional two feet of wire and

1 butt splice that allows the TCW backup (already installed) to add

another layer with less than $5 cost and less than 15 ounces of added

weight.

Anyone interested in why the TCW backup is already installed can me

their phone number to the listed email address and I will call and

explain. The explanation is too long to put it on the list.



On Thu, Aug 17, 2017 at 5:44 PM, user9253 <fransew(at)gmail.com> wrote:

 	  Quote: 	
		   



 Don,

 It is highly unlikely that two failures will occur on the same flight: battery contactor and alternator belt, especially since battery contactors rarely fail.  But let's suppose it happens.  Assume the voltage regulator for the main alternator is set at 14.4 and the voltage regulator for the smaller alternator is set at 13.5 volts.  Both alternators are on-line when the failure occurs, but only the main alternator has been supplying power to the aircraft because its output voltage is higher.  The smaller alternator has been producing voltage but no current.

  When the alternator belt breaks, the system voltage will not immediately drop to zero.  It will take time for the alternator to slow down and stop.  Let's say it takes 0.5 seconds.  During that brief time, the system voltage will fall.  When it gets to 13.5 volts, the smaller alternator will start pushing current because the higher voltage from the main alternator is no longer impeding it.   The smaller alternator should now supply the aircraft power, even with the battery disconnected.  At least that is my theory.  It needs to be confirmed with testing or refuted by Bob.

  If concerned about battery contactor failure, a 40 amp relay could be connected in parallel with it (disabled during engine cranking).

  A concern that I have is activation of the over-voltage protection device.  Will it disable both alternators?  If so, which is the greater danger, an actual over voltage condition, or the loss of both charging systems?  Perhaps the over-voltage set-point for main alternator could be one or two volts less than the set-point for the smaller alternator.



 --------

 Joe Gores





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=471947#471947

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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Aug 18, 2017 7:55 am Post subject: Z13/8 VS Z12

At 10:54 AM 8/16/2017, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Rick Beebe <rick(at)beebe.org>



 A timely question for me. I have a 2001 GlaStar that is about to get a glass panel upgrade. I bought a B&C BD410-H alternator to replace the vacuum pump. Since I believe that would easily be able to power the entire plane and I don't have an engine with electronic ignition I was leaning toward Z12 with no endurance bus. However I've also been studying Z13 to see if it makes more sense. I'm open to opinions on what to do in this relatively green-field application. 	


   Do your load analysis.



   There are examples of Excel spread sheet load studies

   along with some paper forms you can use as

   tools for crafting your own load analysis.



  http://tinyurl.com/9rt6ymn 



   The critical number for your Z12 vs Z13 decision

   is the last column on



  http://tinyurl.com/7jqypwj



   you fill out TWO of these . . . one for

   the battery bus, one for the bus that's

   powered during main alternator out operations.



   The sum of those numbers needs to be on the

   order of 8A or less. The accessories you

   choose to operate in this mode depends

   on your skills for comfortably sustaining

   en route flight to airport of intended

   destination.



   Once the airport is in sight, you can turn

   on any other goodies that improves your

   performance during approach phase . . .

   you'll have plenty of battery left

   to support the op.

   



 

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Aug 18, 2017 8:06 am Post subject: Z13/8 VS Z12

At 07:44 PM 8/17/2017, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 Don,

 It is highly unlikely that two failures will occur on the same flight: battery contactor and alternator belt, especially since battery contactors rarely fail. 	


    In Part 23 aircraft (vast majority of

    single engine aircraft), system reliability

    studies (statistical analysis) are not required

    and stacked failures are never considered.



    The likelihood of compounding failures

    occurring while consuming one tank full of fuel is

    exceedingly remote. Some failures, like

    belts breaking, are WWwwaaayyy down on the

    list of concerns . . . anyone who suffers

    a broken belt has been ignoring it too

    long.



      



 

 

   Bob . . .

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