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Question about B&C Regulators

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aadamson(at)highrf.com
Guest

Posted: Sun Jul 29, 2007 6:31 pm Post subject: Question about B&C Regulators

So, I have 2 LR-3C-28's at the moment to be used with a stock continental

100A 28V alternator and an SD-20 backup alternator..... BUT, a friend came

by and told me that B&C recommends that you use the LS-1A instead of the

LR-3C with the SD-20.



Anyone know why, or if it really matters?  I plan to call B&C in the next

couple of days to get their side of the story.  I did notice that the LS-1A

doesn't have a huge heat sink like the 28v version of the LR-3C.  But I have

no idea what else is different under the hood?



Alan

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Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Sun Jul 29, 2007 8:14 pm Post subject: Question about B&C Regulators

Alan, I believe that the issue is How the SD20 is being used, I'm 

building to a Z14 and as I understand it, if you are planning on having 

both alternators continuously online at the same time you use the 

regulators you have. If you plan on only using the SD20 as a back-up 

then the other regulator is the choice.



Deems Davis # 406

'Its all done....Its just not put together'

http://deemsrv10.com/



Alan K. Adamson wrote:

 	  Quote: 	
		   



 So, I have 2 LR-3C-28's at the moment to be used with a stock continental

 100A 28V alternator and an SD-20 backup alternator..... BUT, a friend came

 by and told me that B&C recommends that you use the LS-1A instead of the

 LR-3C with the SD-20.



 Anyone know why, or if it really matters?  I plan to call B&C in the next

 couple of days to get their side of the story.  I did notice that the LS-1A

 doesn't have a huge heat sink like the 28v version of the LR-3C.  But I have

 no idea what else is different under the hood?



 Alan

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nuckollsr(at)cox.net
Guest

Posted: Mon Jul 30, 2007 5:07 am Post subject: Question about B&C Regulators

At 10:28 PM 7/29/2007 -0400, you wrote:



 	  Quote: 	
		  

<aadamson(at)highrf.com>



So, I have 2 LR-3C-28's at the moment to be used with a stock continental

100A 28V alternator and an SD-20 backup alternator..... BUT, a friend came

by and told me that B&C recommends that you use the LS-1A instead of the

LR-3C with the SD-20.



Anyone know why, or if it really matters?  I plan to call B&C in the next

couple of days to get their side of the story.  I did notice that the LS-1A

doesn't have a huge heat sink like the 28v version of the LR-3C.  But I have

no idea what else is different under the hood?


	


   I designed both of those regulators. You can use the LR-3 series devices

   on the SD-20 in 14 volt applications . . . in fact, I believe that's

   what's currently recommended. However, there is no difference between

   the SD-20 used in 14 volt systems and 28 volts systems . . . only

   the regulator. To keep from burning the SD-20's 14V field winding by putting

   28 volts on it, we crafted a special regulator that is in fact, a 0-15v

   switchmode power supply. The output of the power supply is steered by

   the 28V regulator electronics to achieve the desired bus voltage but

   with a hard upper limit of 15V applied to the field such that it's

   never in danger of smoking.



   Bob . . .



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

        ( "Physics is like sex: sure, it may   )

        ( give some practical results, but     )

        ( that's not why we do it."            )

        (                                      )

        (                 Richard P. Feynman   )

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

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nuckollsr(at)cox.net
Guest

Posted: Mon Jul 30, 2007 5:17 am Post subject: Question about B&C Regulators

At 09:13 PM 7/29/2007 -0700, you wrote:



 	  Quote: 	
		  



Alan, I believe that the issue is How the SD20 is being used, I'm building 

to a Z14 and as I understand it, if you are planning on having both 

alternators continuously online at the same time you use the regulators 

you have. If you plan on only using the SD20 as a back-up then the other 

regulator is the choice.


	


    Close . . . but the regulator for using the SD-20 as a same-bus

    standby is a little different yet. The low voltage warning

    section of the SB series regulators is replaced with an overload

    detection and annunciation system. When the SD-20 shares a common

    bus with another alternator, it's set-point is about 1.0 volts

    BELOW that of the main alternator. When the main alternator fails

    or is turned off, the bus voltage sags and the SD-20 comes alive

    in an attempt to pick up all present loads. IF those loads exceed

    20A, the ALTERNATOR LOADED light flashes. The pilot then reduces

    loads to stop the flashing which indicates that the SD-20 is

    no operating with designed limits.



    I believe that installation instructions and operating details

    for the LR, LS and SB series regulators are available from

    B&C's website.



    Bob . . .

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aadamson(at)highrf.com
Guest

Posted: Mon Jul 30, 2007 6:57 am Post subject: Question about B&C Regulators

Deems, thanks for the note.  I would agree with your comments if they said

to use the SB1B-28, but we are talking about the LS-1A.  The justification

that B&C used with my friend was that this regulator helps the SD-20 make 28

volts???



Ok, so is there some magic that allows it to make those volts at lower RPM

settings?  That would be a good thing I suppose...



I'll be calling B&C today to find out more.



Alan 



--

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aadamson(at)highrf.com
Guest

Posted: Mon Jul 30, 2007 6:59 am Post subject: Question about B&C Regulators

Bob,



Thanks for the note.



So am I to assume from your comments, that in a dual alt, dual 24v battery

system, that I should use the LS-1A with the SD-20 *instead* of another

LR-3C-28?



Are you also saying that the LR-3C-28 *could* damage the SD-20 if used with

it?



Thanks again,

Alan 



--

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nuckollsr(at)cox.net
Guest

Posted: Mon Jul 30, 2007 9:42 am Post subject: Question about B&C Regulators

At 10:59 AM 7/30/2007 -0400, you wrote:



 	  Quote: 	
		  



Bob,



Thanks for the note.



So am I to assume from your comments, that in a dual alt, dual 24v battery

system, that I should use the LS-1A with the SD-20 *instead* of another

LR-3C-28?


	


   Correct.

 	  Quote: 	
		  Are you also saying that the LR-3C-28 *could* damage the SD-20 if used with

it?


	


   ABSOLUTELY guaranteed that it would damage the SD-20.

   Bob . . .

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