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SD-8 ALTERNATOR MOD FOR SELF EXCITATION

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nuckollsr(at)cox.net
Guest

Posted: Wed Jul 19, 2006 8:01 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

Thanks to the diligence of Jim McCulley we've tried a

modification to SD-8 alternator installations that

appears to be a good solution for getting the SD-8

to self excite. See revision L to Figure Z-25

at:



http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z25L.pdf



The Autocad version is at:



http://www.aeroelectric.com/PPS/ACAD_Architecture_Dwgs/Z24-25L.dwg



It's also been added to Appendix Z which steps the chapter up

to Revison J at:



http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf



See Note 25 and Figure Z-25



When I get time, I'll update all the other z-figures that use

an SD-8 to include the self-excitation feature.



Thanks again Jim!



Bob . . .



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

( Experience and common sense cannot be )

( replaced with policy and procedures. )

( R. L. Nuckolls III )

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



        Bob . . .

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

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

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

Bob McC

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

Posted: Wed Jul 19, 2006 9:23 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

Thanks Bob (and Jim)   - - - BUT - - - according to this modified version of

Z-25 the battery still needs to be in "good functioning condition" in order

to energize the S704-1 relay thus connecting the now self excited  SD-8 to

the rest of the electrical system to utilize its output. If the battery is

of sufficient capacity to do this why couldn't we have used this same

capacity to excite the SD-8. What did we gain by its self excitation?? What

am I missing?? I would think an additional modification to Z-25 would be

required to actually make use of this self excitation. No ??



Bob McC

---

_________________
Bob McC
Falco #908
(just starting)

nuckollsr(at)cox.net
Guest

Posted: Thu Jul 20, 2006 4:41 am Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

Good eye! I was so focused on the SD-8 I dropped the ball

on the system integration. The drawings have been corrected

to add steering didoes so that the disconnect relay will pull in

from either battery or alternator voltage -AND- (in most cases)

still have benefit of the battery to trip the OV crowbar.



Bob . . .



At 01:16 AM 7/20/2006 -0400, you wrote:



[quote]

<robert.mccallum2(at)sympatico.ca>



Thanks Bob (and Jim)   - - - BUT - - - according to this modified version of

Z-25 the battery still needs to be in "good functioning condition" in order

to energize the S704-1 relay thus connecting the now self excited  SD-8 to

the rest of the electrical system to utilize its output. If the battery is

of sufficient capacity to do this why couldn't we have used this same

capacity to excite the SD-8. What did we gain by its self excitation?? What

am I missing?? I would think an additional modification to Z-25 would be

required to actually make use of this self excitation. No ??



Bob McC

---

rv9jim(at)juno.com
Guest

Posted: Thu Jul 20, 2006 10:20 am Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

Bob,

        I just down loaded the drawing I found the dual diodes at the

coil of the relay.  Is this the way to energize the coil with the SD8  on

line only?



Jim Nelson

nuckollsr(at)cox.net
Guest

Posted: Thu Jul 20, 2006 5:15 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

At 02:16 PM 7/20/2006 -0400, you wrote:



 	  Quote: 	
		  



Bob,

         I just down loaded the drawing I found the dual diodes at the

coil of the relay.  Is this the way to energize the coil with the SD8  on

line only?


	


   It provides coil excitation for when ONLY the SD-8 is running

   but also provides a path from the battery when it's on line

   for providing the high current, short duration source necessary

   for crowbar ov protection.



   I've got a new LV/OV monitoring system coming onto the 'Connections

   pages in the next few weeks that will provide an alternative to the

   schematic published. In the mean time, the drawing provided works

   too.



   Bob . . .

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

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

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

mcculleyja(at)starpower.n
Guest

Posted: Fri Jul 21, 2006 1:00 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

Bob,



Thanks to you for putting together this final product. I am happy that 

you were pleased with my help in conducting the experiment.



I'm puzzled, however, by the values of the resistors you listed on the 

updated Z-25 drawing. In my message of 5/6/2006, I reported that I found 

it necessary to use 15k ohm resistance in series with the added diodes 

to avoid the voltage across the capacitor rising above 16 volts while 

the SD-8 was not switched onto the buss during maximum RPM.



Also, in my 6/19/2006 message the operating data was acquired while 

using 15k resistance in series with the diodes and 3k resistance across 

the capacitor. The overall performance and reliability of coming on-line 

under all realistic RPM conditions seemed ideal--or did I miss something?



Did you find the lower resistance values of 3k and 1k, respectively, 

necessary for overall better functioning? Just curious.



Jim McCulley

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



Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckollsr(at)cox.net>

 

 

 Thanks to the diligence of Jim McCulley we've tried a

 modification to SD-8 alternator installations that

 appears to be a good solution for getting the SD-8

 to self excite. See revision L to Figure Z-25

 at:

 

 http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdf/Z25L.pdf

 

 The Autocad version is at:

 

 http://www.aeroelectric.com/PPS/ACAD_Architecture_Dwgs/Z24-25L.dwg

 

 It's also been added to Appendix Z which steps the chapter up

 to Revison J at:

 

 http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf

 

 See Note 25 and Figure Z-25

 

 When I get time, I'll update all the other z-figures that use

 an SD-8 to include the self-excitation feature.

 

 Thanks again Jim!

 

 Bob . . .

 

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

 ( Experience and common sense cannot be )

 ( replaced with policy and procedures. )

 ( R. L. Nuckolls III )

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

 

 

 

        Bob . . .

 

 

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

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

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

 

 

 

 

 http://www.matronics.com/Navigator?AeroElectric-List

 http://wiki.matronics.com

nuckollsr(at)cox.net
Guest

Posted: Fri Jul 21, 2006 7:55 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

At 04:32 PM 7/21/2006 -0400, you wrote:



 	  Quote: 	
		  

<mcculleyja(at)starpower.net>



Bob,



Thanks to you for putting together this final product. I am happy that you 

were pleased with my help in conducting the experiment.



I'm puzzled, however, by the values of the resistors you listed on the 

updated Z-25 drawing. In my message of 5/6/2006, I reported that I found 

it necessary to use 15k ohm resistance in series with the added diodes to 

avoid the voltage across the capacitor rising above 16 volts while the 

SD-8 was not switched onto the buss during maximum RPM.


	


    The two resistors form a voltage divider. The voltage across

    the capacitor in a totally uncontrolled condition will be a function

    of the alternator's pk=pk output at the time. Totally unloaded and

    at cruise RPM, I seep to recall that the alternator's output was

    on the order of



    Also, you mentioned using a 1KuF capacitor. The rule of thumb for

    capacitors in this application is 1Kuf per ampere of system

    capacity. so 10KuF is the recommended minimum and larger doesn't

    hurt anything. I maintained the same ratio (3:1) for the resistor

    values in an effort to bring the source impedance of the voltage

    divider down to speed things up with the larger capacitor size.

 	  Quote: 	
		  Also, in my 6/19/2006 message the operating data was acquired while using 

15k resistance in series with the diodes and 3k resistance across the 

capacitor. The overall performance and reliability of coming on-line under 

all realistic RPM conditions seemed ideal--or did I miss something?


	


    Nope, your experiments were entirely valid. We're just

    fine tuning the recipe . . .

 	  Quote: 	
		  Did you find the lower resistance values of 3k and 1k, respectively, 

necessary for overall better functioning? Just curious.


	


     . . . 99.9% sure the lower values are a good move based on common

    sense and understanding of how the "fix" works. I'd like

    to send you a set of components to install permanently both

    to photograph for some installation instructions and to validate

    the final design.



    I've also forwarded the data on our effort to Tim (at) B&C. He'll

    be working with their supplier of the regulator. All of the

    components we've added could probably go INSIDE the regulator.



    I think we've got a working configuration but we're not yet

    arrived at the elegant solution.



    Bob . . .

mcculleyja(at)starpower.n
Guest

Posted: Sat Jul 22, 2006 6:29 am Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

Bob,



I've noted a few questions within your following response below:



Jim

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



Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckollsr(at)cox.net>

 

 At 04:32 PM 7/21/2006 -0400, you wrote:

 

> 

> <mcculleyja(at)starpower.net>

>

> Bob,

>

> Thanks to you for putting together this final product. I am happy that 

> you were pleased with my help in conducting the experiment.

>

> I'm puzzled, however, by the values of the resistors you listed on the 

> updated Z-25 drawing. In my message of 5/6/2006, I reported that I 

> found it necessary to use 15k ohm resistance in series with the added 

> diodes to avoid the voltage across the capacitor rising above 16 volts 

> while the SD-8 was not switched onto the buss during maximum RPM.

 

 

    The two resistors form a voltage divider. The voltage across

    the capacitor in a totally uncontrolled condition will be a function

    of the alternator's pk=pk output at the time. Totally unloaded and

    at cruise RPM, I seep to recall that the alternator's output was

    on the order of


	


What is missing in the above sentence after the word "of"?

 	  Quote: 	
		   

    Also, you mentioned using a 1KuF capacitor. The rule of thumb for

    capacitors in this application is 1Kuf per ampere of system

    capacity. so 10KuF is the recommended minimum and larger doesn't

    hurt anything. I maintained the same ratio (3:1) for the resistor

    values in an effort to bring the source impedance of the voltage

    divider down to speed things up with the larger capacitor size.


	


Yes, I tested the extremes of capacitance as well as resistance values 

by using cockpit adjustable pots, as you had suggested in an earlier 

comment. It was from these tests that I concluded the values of 15k and 

3k resistors were good at all operating conditions. The capacitance 

value is quite acceptable over a large range, but 1kmf is definitely 

below the lowest acceptable value.

 	  Quote: 	
		   

 

> Also, in my 6/19/2006 message the operating data was acquired while 

> using 15k resistance in series with the diodes and 3k resistance 

> across the capacitor. The overall performance and reliability of 

> coming on-line under all realistic RPM conditions seemed ideal--or did 

> I miss something?

 

 

    Nope, your experiments were entirely valid. We're just

    fine tuning the recipe . . .

 

 

> Did you find the lower resistance values of 3k and 1k, respectively, 

> necessary for overall better functioning? Just curious.

 

 

     . . . 99.9% sure the lower values are a good move based on common

    sense and understanding of how the "fix" works. I'd like

    to send you a set of components to install permanently both

    to photograph for some installation instructions and to validate

    the final design.

 

    I've also forwarded the data on our effort to Tim (at) B&C. He'll

    be working with their supplier of the regulator. All of the

    components we've added could probably go INSIDE the regulator.


	


Is it possible that B&C would be interested and better equipped to 

verify the optimum component values and physical layout via motorized 

bench testing wherein the conditions can be better stabilized and 

controlled than is the case during either engine ground runs or 

in-flight testing as I did? For instance, I noted an apparent variable 

in results that I suspect was related to changing component temperatures 

over time. This may not be a significant variable but did make 

repeatability of data somewhat less than ideal.

 	  Quote: 	
		   

    I think we've got a working configuration but we're not yet

    arrived at the elegant solution.

 

    Bob . . .

 

 

 

 

 http://www.matronics.com/Navigator?AeroElectric-List

 http://wiki.matronics.com

jgswartout(at)earthlink.n
Guest

Posted: Sat Jul 22, 2006 3:12 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

So, is the "L" version, dated 7-18-06, accessible via the first link in your

7-20-06 post, the right one for now?  If not, please direct me to the

corrected drawing.  Thanks Bob.



John



--

nuckollsr(at)cox.net
Guest

Posted: Sat Jul 22, 2006 6:33 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

At 07:01 PM 7/22/2006 -0400, you wrote:



 	  Quote: 	
		  

<jgswartout(at)earthlink.net>



So, is the "L" version, dated 7-18-06, accessible via the first link in your

7-20-06 post, the right one for now?  If not, please direct me to the

corrected drawing.  Thanks Bob.


	


   Yes. I updated the "L" version and left the link alone.



   Bob . . .

nuckollsr(at)cox.net
Guest

Posted: Tue Jul 25, 2006 8:05 pm Post subject: SD-8 ALTERNATOR MOD FOR SELF EXCITATION

 	  Quote: 	
		  

Is it possible that B&C would be interested and better equipped to verify 

the optimum component values and physical layout via motorized bench 

testing wherein the conditions can be better stabilized and controlled 

than is the case during either engine ground runs or in-flight testing as 

I did? For instance, I noted an apparent variable in results that I 

suspect was related to changing component temperatures over time. This may 

not be a significant variable but did make repeatability of data somewhat 

less than ideal.


	


   Absolutely! That's why I've forwarded the data to Tim at B&C.

   I presently have no working relationship with B&C so this

   activity is being offered to them as advisory data as opposed

   to a directed development effort.



   Bob . . .

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