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OV Module additional requirement

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bob(at)flyboybob.com
Guest

Posted: Sat Sep 02, 2006 9:43 am Post subject: OV Module additional requirement

Bob,



I have upgraded my engine from mag to electronic ignition and carb to fuel

injection.  This has increased the electrical demand far in excess of the 20

amp alternator that is supplied with my engine.  I am using Z13-20 with a 40

amp alternator installed in the mag drive of the engine.



My load analysis shows 59 amps with everything on (including pitot heat).

Therefore I would like to be able to run both alternators together as my

standard operation.  Now lets make the assumption that one of the

alternators has an OV event.  Using the existing Crowbar OVM revE as a base

line I would like to know if it is possible to remove the wire between pinA

of the Gate S6025L, and add an additional output from the OVM to be the trip

for the alternator field.  The existing positive connection of the OVM would

be connected to the alternator B+ as a sense lead.



I have a schematic of this idea at

http://flyboybob.com/images/kr2/n52bl/electric%20and%20instrument/ov001-rev2

-4.jpg to illistrate my question.



The power distribution has the two alternators each with a separate OVM

comming together at the battery contactor on opposite sides which puts the

battery between B+ power feeds of the two alternators.



That's the background, now the question:



Would an OVMs be able to sence the offending high voltage alternator and

only trip that one alternator off line?  Or would the battery not be able to

clamp the OV event long enough to prevent the OVM on the good alternator

from tripping too?



Regards,



Bob Lee

N52BL  KR2

Suwanee, GA

91% done only 65% to go!

bob(at)flyboybob.com
Guest

Posted: Thu Sep 07, 2006 9:14 am Post subject: OV Module additional requirement

OK 'Lectron heads, let me know,  did question just got dropped in the midst

of all the George-bantor, or is it too dumb to get an answer?



The questions:



1. can the OVM be modified to allow for three inputs: sense, trip, and

ground?  (I don't want to crowbar the same place that I want to measure the

voltage.)



2. Can one OVM detect and react to an OV event fast enough to trip the

correct alternator in a two alternator/OVM installation?



The deatils are in the attached message.



Regards,



Bob Lee

N52BL  KR2

Suwanee, GA

91% done only 65% to go!

--

klehman(at)albedo.net
Guest

Posted: Thu Sep 07, 2006 6:42 pm Post subject: OV Module additional requirement

Hi Bob Lee



With paralleled alternators you probably can't really have an 

overvoltage due to a single failure with such a heavilly loaded system. 

If either alternator running full on at 100% output would still not 

exceed the system load, then the second alternator would just reduce its 

output (although it might well oscillate). I actually observed something 

similar today. After a night flight I had inadvertantly left a fuel pump 

on that drained one battery. It seemed like an opportunity to experiment 

a bit with my Z-14 architecture so I ran the engine. Bad idea I guess as 

the 20amp PM alternator now seems to want to run full on. However in the 

short term it does not come close to tripping the OVP as long as the 

batteries are paralleled. With 20 amps or more load the voltage stays 

completely normal.



Back to your situation - even with small loads I would not expect an OVM 

to trip only the problem alternator if two alternators are paralleled 

and one goes to max output. Two regulators or two OVMs will always have 

slightly different control voltages.  There is some discussion on the 

difficulties of paralleling alternators in the archives. You might want 

to consider a larger main alternator unless it is only temporary loads 

like landing lights that is bringing you up to 59 amps. Certainly you 

can build an OVM with a separate sense wire but I haven't looked at your 

proposed method.



Ken



Bob Lee wrote:



[quote]



OK 'Lectron heads, let me know,  did question just got dropped in the midst

of all the George-bantor, or is it too dumb to get an answer?



The questions:



1. can the OVM be modified to allow for three inputs: sense, trip, and

ground?  (I don't want to crowbar the same place that I want to measure the

voltage.)



2. Can one OVM detect and react to an OV event fast enough to trip the

correct alternator in a two alternator/OVM installation?



The deatils are in the attached message.



Regards,



Bob Lee

N52BL  KR2

Suwanee, GA

91% done only 65% to go!

--

nuckollsr(at)cox.net
Guest

Posted: Fri Sep 08, 2006 4:45 am Post subject: OV Module additional requirement

At 01:08 PM 9/7/2006 -0400, you wrote:



 	  Quote: 	
		  



OK 'Lectron heads, let me know,  did question just got dropped in the midst

of all the George-bantor, or is it too dumb to get an answer?



The questions:



1. can the OVM be modified to allow for three inputs: sense, trip, and

ground?  (I don't want to crowbar the same place that I want to measure the

voltage.)



2. Can one OVM detect and react to an OV event fast enough to trip the

correct alternator in a two alternator/OVM installation?



The deatils are in the attached message.


	


   Your system narrative seems to describe two alternators

   running in parallel to a single battery. You've also

   expressed a desire to rate your system's load carrying

   ability by a dependence on both alternators running

   to drive a single bus.



   Running two or more engine driven power sources in parallel

   takes special regulators that talk to each other, compare

   present loads with respect to capacity of each alternator

   and agree on how the loads are divided so that each machine

   shares total load in proportion to it's ratings.



   On the Hawker 800, we can run both engine generators and

   the APU simultaneously and even tho the apu is a much smaller

   generator, one can check the running loads and see that

   all machines are carrying their "fair" share . . . i.e.

   all read close to the same percentage of total load.



   I've not studied the details of the generator control units

   supplied with this system but I'd be surprised if the built-in

   OV detection and shut down systems are not smart enough to

   know who is responsible for an OV condition; the generator

   over which I have responsibility -OR- some other machine

   in the system.



   If you use B&C regulators in some combination like that

   depicted in Z-12 (Main and Aux alternators driving a common

   bus), the regulators are designed to differentiate between

   an OV condition caused by "my alternator" or the "other guy's

   alternator" and respond accordingly. We call it selective

   OV trip.



   Without knowing more about the hardware you selected to

   deduce whether or not selective trip is possible/practical

   for your system.



   Let's look at the basics first. Under what conditions do

   you anticipate a 59A running load? Have you crafted a load

   analysis and filled out a form like:



http://www.aeroelectric.com/PPS/Load_Analysis/Blank_Form.pdf



   I'm skeptical that you really need a 59A running capacity

   unless you have some form of electric heated windows, etc.

   Let's look over your numbers first.  If you've a mind to

   use Excel as opposed to a paper form, the directory at:



http://www.aeroelectric.com/PPS/Load_Analysis



   . . . has several exemplar Load Analysis spread sheets

   you are invited to exploit for data and/or modify for

   your own use as you wish.



   When this is complete, let's revisit you alternator

   choices/options and see what it takes to make it all work.

   Bob . . .

N6030X(at)DaveMorris.com
Guest

Posted: Fri Sep 08, 2006 5:35 am Post subject: OV Module additional requirement

Is anybody else having trouble getting Excel to open these?  It locks 

up everytime I try one of them and gives me an error that Excel is 

trying to communicate with some other program using OLE.



Dave Morris



At 07:44 AM 9/8/2006, you wrote:

   I'm skeptical that you really need a 59A running capacity

 	  Quote: 	
		     unless you have some form of electric heated windows, etc.

   Let's look over your numbers first.  If you've a mind to

   use Excel as opposed to a paper form, the directory at:



http://www.aeroelectric.com/PPS/Load_Analysis



   . . . has several exemplar Load Analysis spread sheets

   you are invited to exploit for data and/or modify for

   your own use as you wish.

aadamson(at)highrf.com
Guest

Posted: Fri Sep 08, 2006 6:17 am Post subject: OV Module additional requirement

Dave, just checked with excel 2003 and they opened fine...



Alan 



--

brian-av(at)lloyd.com
Guest

Posted: Fri Sep 08, 2006 8:32 am Post subject: OV Module additional requirement

On Sep 8, 2006, at 6:34 AM, Dave N6030X wrote:



 	  Quote: 	
		   

 <N6030X(at)DaveMorris.com>



 Is anybody else having trouble getting Excel to open these?  It  

 locks up everytime I try one of them and gives me an error that  

 Excel is trying to communicate with some other program using OLE.


	


Try grabbing a copy of OpenOffice. (http://www.openoffice.org) I find  

it seems to do well with many different file formats. The price is  

right. It is good enough that I am moving away from the Microsoft  

office suite as a result.



Brian Lloyd                         361 Catterline Way

brian HYPHEN av AT lloyd DOT com    Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

N6030X(at)DaveMorris.com
Guest

Posted: Fri Sep 08, 2006 9:31 am Post subject: OV Module additional requirement

I've got the latest updated copy of Excel 2002 

SP3 but it's trying to do something strange with 

these particular files.  I don't have this problem with other Excel files.

Dave

At 11:31 AM 9/8/2006, you wrote:

 	  Quote: 	

On Sep 8, 2006, at 6:34 AM, Dave N6030X wrote:

>

><N6030X(at)DaveMorris.com>

>

>Is anybody else having trouble getting Excel to open these?  It

>locks up everytime I try one of them and gives me an error that

>Excel is trying to communicate with some other program using OLE.

Try grabbing a copy of OpenOffice. (http://www.openoffice.org) I find

it seems to do well with many different file formats. The price is

right. It is good enough that I am moving away from the Microsoft

office suite as a result.

Brian Lloyd                         361 Catterline Way

brian HYPHEN av AT lloyd DOT com    Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

bob(at)flyboybob.com
Guest

Posted: Fri Sep 08, 2006 9:49 am Post subject: OV Module additional requirement

Bob,



Thanks for your reply.  I can tell that the path I was trying to go down is

not the one to take (two alternators on one bus).  The load analysis shows

15 amps on the battery bus (electronic ignition/fuel injection), 6 amps on

the endurance bus (minimum equipment for safe flight) and 36 amps on the

Main bus.

It is posted at: http://flyboybob.com/web_pages/kr2/index.htm, if you click

the link to "electrical" in the left frame the first thing that comes up is

the load analysis.



I'll go with the 40 amp main alternator and 20 amp back up and just do the

switching manually.  It seems that making it automatic will not be as simple

as I had hopped.



Once again, thanks for sharing your experience.



Regards,



Bob Lee

N52BL  KR2

Suwanee, GA

91% done only 65% to go!

--

nuckollsr(at)cox.net
Guest

Posted: Fri Sep 08, 2006 10:40 am Post subject: OV Module additional requirement

At 01:43 PM 9/8/2006 -0400, you wrote:



 	  Quote: 	
		  



Bob,



Thanks for your reply.  I can tell that the path I was trying to go down is

not the one to take (two alternators on one bus).  The load analysis shows

15 amps on the battery bus (electronic ignition/fuel injection), 6 amps on

the endurance bus (minimum equipment for safe flight) and 36 amps on the

Main bus.

It is posted at: http://flyboybob.com/web_pages/kr2/index.htm, if you click

the link to "electrical" in the left frame the first thing that comes up is

the load analysis.



I'll go with the 40 amp main alternator and 20 amp back up and just do the

switching manually.  It seems that making it automatic will not be as simple

as I had hopped.



Once again, thanks for sharing your experience.


	


   Not sure you need to resort to manual switching. If you wire

   per Z-12 with B&C hardware, automatic assumption of loads by

   the auxiliary alternator is built in. Both alternators are ON

   all the time . . . Aux alternator is set for 13.0 volts while main

   alternator is set for 14.2 volts. The aux alternator regulator sees

   "too high" bus voltage and relaxes. If main altenrator goes off

   line, bus voltage sags and aux alternator comes alive. If loads

   on the Aux Alternator exceed rated output of 20A, then the "AUX

   ALT LOADED" light flashes. You turn things off until the light

   stops flashing.



   But your load analysis suggests that Z-13/8 would be all you

   need. How much RUNNING current does the pitot heater draw when

   submerged in an ice bath? This is the real load-analysis current.



   Are the position lights LED? if not, 2.0A for nav lights is

   too low.



   The dynamo relay would be an E-bus load, not a battery bus load.



   Ignition of 8A is REALLY big . . . what engine are you using

   and what ignition system?



   Landing and taxi lights are generally not combined with pitot

   heat. You may adopt an operating protocol that runs pitot heat

   in VMC when lights would be off.



   Let's tweak this analysis a bit. I'm not convinced that you

   need a 40/20 system . . . and 40/8 may well get done what you

   need to do.



   Bob . . .

bob(at)flyboybob.com
Guest

Posted: Sat Sep 09, 2006 1:16 am Post subject: OV Module additional requirement

Bob Nuckolls wrote: (my reply in << brackets >>

   Not sure you need to resort to manual switching. If you wire

   per Z-12 with B&C hardware, automatic assumption of loads by

   the auxiliary alternator is built in. Both alternators are ON

   all the time . . . Aux alternator is set for 13.0 volts while main

   alternator is set for 14.2 volts. The aux alternator regulator sees

   "too high" bus voltage and relaxes. If main altenrator goes off

   line, bus voltage sags and aux alternator comes alive. If loads

   on the Aux Alternator exceed rated output of 20A, then the "AUX

   ALT LOADED" light flashes. You turn things off until the light

   stops flashing.

<<  The 20 amp dynamo supplied with the engine has a regulator that seems to

be a type of zenor that meerly clamps the voltage to a limit.  There are

only three connections on the regulator:  AC(1), [AC(2) and +12], and

ground.  I cannot use the B&C hardware here because it is a permanant magnet

unit, therefore Z-13. >>



   But your load analysis suggests that Z-13/8 would be all you

   need. How much RUNNING current does the pitot heater draw when

   submerged in an ice bath? This is the real load-analysis current.

<<  Will need to test this because I don't know - see below  >>



   Are the position lights LED? if not, 2.0A for nav lights is

   too low.

<< Yes, LED >>



   The dynamo relay would be an E-bus load, not a battery bus load.

<<  It ends up on the battery bus because I have used the method suggested

on Z-13/8 that brings the ground to the panel through a circuit-breaker that

gets tripped for an OV event.  The positive side of the relay is just

connected to the b+ lead on the battery side of the disconnect relay. >>



   Ignition of 8A is REALLY big . . . what engine are you using

   and what ignition system?

<<  Great Plains Aircraft Supply 2600cc.  It is an auto conversion based on

the VW TypeIV engine.  The ignition is a Comp-u-Fire electronic ignition.

There are several flying and they measure 8 amps. >>



   Landing and taxi lights are generally not combined with pitot

   heat. You may adopt an operating protocol that runs pitot heat

   in VMC when lights would be off.

<<  Certainly this is an option that can work.  I was trying to develop a

solution that reduced the number of electrical events that the pilot got

involved in.  Let the airplane solve any problem it can and reduce the types

of events that the pilot was responsible for managing is the design goal

here.  In reality, I don't intend to need pitot heat by flying in VMC.  I

meerly want to have the legal equipment to allow me to regularly file IFR.

I find that flying IFR all the time makes you a better pilot on those

extremely rare ocassions where you end up in less than VFR weather by

mistake.  If pitot heat gets turned on though, the charging system needs to

handle it. >>



   Let's tweak this analysis a bit. I'm not convinced that you

   need a 40/20 system . . . and 40/8 may well get done what you

   need to do.

<<  The engine is supplied with a 20 amp perminant-magnet dynamo so the 8/20

decision has already been made by the engine supplier.  The 40 amp

alternator is from a Honda Gold Wing motorcycle.  I selected it because it

is driven off the transmission end of the primary drive (1/2 engine speed).

This makes the rpm range of my engine a very close match to the design rpm

range of this alternator.  I have modified it's mounting to allow it to be

placed in the mag drive of my engine. I also modified the alternator to

remove the internal regulator and use an external regulator.  The faston

male connector that was the idot light is now the field input. >>



   Bob . . .

<<  me to! >>

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