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donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Fri Jun 26, 2015 3:34 am Post subject: Alternator problem?

I'm in the process of trying to track down an over voltage fault. 



So far the engine runs that I've been doing have been relatively short duration (mostly around 5-10min) while I'm getting the engine dialed in. On about 4 occasions I've noticed the alternator circuit has faulted for "over voltage". 



I'm running a 28v electrical system 

VP-X Pro

B&C LR3C voltage regulator

Kelly Aerospace 50a alternator

Continental IO-550 engine. 



Vertical Power and B&C have had me check a number things.  All checks have shown voltage levels, drops and wire resistance to be well within parameters. 



B&C is recommending to pull the alternator and have it checked. 



I"m just wondering if anyone has run into anything similar with these alternators before I pull it ship it out.

user9253

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

Posted: Fri Jun 26, 2015 4:48 am Post subject: Re: Alternator problem?

I think it is more likely that there is a bad (intermittent) connection or faulty voltage regulator than a problem with the alternator.  The best way to find a bad connection is to make voltage measurements when the circuit is under heavy load.  A high wattage lamp can be used to temporarily load the circuit for voltage testing.  Particular attention should be given to LR3C terminals 6 and 7 and the associated wiring.  If a high wattage lamp is connected between terminals 6 & 7, the voltage between those two terminals should be close to battery voltage.

Joe

_________________
Joe Gores

jluckey(at)pacbell.net
Guest

Posted: Fri Jun 26, 2015 7:25 am Post subject: Alternator problem?

Don,



First step is to determine if you are actually experiencing a fault or just a bad indication.



Which system is giving you the over voltage fault error? The VP, an over voltage module, something else?



Do you have a digital volt meter that remembers the highest peak voltage?



-Jeff



Sent from my iPad



 	  Quote: 	
		   On Jun 26, 2015, at 04:34, donjohnston <don(at)velocity-xl.com> wrote:

 

 

 

 I'm in the process of trying to track down an over voltage fault. 

 

 So far the engine runs that I've been doing have been relatively short duration (mostly around 5-10min) while I'm getting the engine dialed in. On about 4 occasions I've noticed the alternator circuit has faulted for "over voltage". 

 

 I'm running a 28v electrical system 

 VP-X Pro

 B&C LR3C voltage regulator

 Kelly Aerospace 50a alternator

 Continental IO-550 engine. 

 

 Vertical Power and B&C have had me check a number things.  All checks have shown voltage levels, drops and wire resistance to be well within parameters. 

 

 B&C is recommending to pull the alternator and have it checked. 

 

 I"m just wondering if anyone has run into anything similar with these alternators before I pull it ship it out.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=444057#444057

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Fri Jun 26, 2015 9:05 am Post subject: Re: Alternator problem?

As it has been explained to me, the voltage regulator is determining the fault. The VP-X is reporting the fault.



My meter has a hold feature but it's manual, not a peak hold.

jluckey(at)pacbell.net
Guest

Posted: Fri Jun 26, 2015 10:33 am Post subject: Alternator problem?

Don,

That regulator uses the "crowbar" technique to handle an over-voltage condition.  Which means that it will pop its own circuit breaker to shut itself off when buss voltage gets too high.



So, is it the case that the electronic circuit breaker in the VP-X which feeds the regulator is "popping"?  (I'm not very familiar w/ the VP-X so I don't know how it indicates when one of its electronic circuit breakers pops.)

Does the VP-X have an alarm channel for Over-Voltage?  If so, was that alarm triggered?



-Jeff

  



     On Friday, June 26, 2015 10:16 AM, donjohnston <don(at)velocity-xl.com> wrote:

  

  



 --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com (don(at)velocity-xl.com)>



As it has been explained to me, the voltage regulator is determining the fault. The VP-X is reporting the fault.



My meter has a hold feature but it's manual, not a peak hold.





Read this topic online here:



http://forums.matronics.com/v="http://www.matronics.com/Navigator?AeroElectric-List" target="_blank"orums.matronics.com/" target="_blank">http://forums.matronics.com

;                   -Matt Dralcontribution" target="_blank">http://www.matronics.com/contribution

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jun 26, 2015 4:00 pm Post subject: Alternator problem?

At 12:05 PM 6/26/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com>



 As it has been explained to me, the voltage regulator is determining the fault. The VP-X is reporting the fault.



 My meter has a hold feature but it's manual, not a peak hold. 	


    If we were conducting this investigation

    in B-31 at Beech (Flight Test) we would

    get out a data acquisition system capable

    gathering 5 channels of voltage at 2% 

    or better accuracy for 100 samples per

    second or faster.



    Monitor battery voltage at the battery



    Monitor B-terminal voltage at the alternator



    Monitor Alternator Field voltage at the

    alternator



    Monitor Bus Sense voltage at the regulator



    Monitor Bus Voltage at the Regulator.



    Then go fly and see if the problem will

    duplicate.



    The data traces will reveal how the major

    players behave before, during and after

    the event . . . and probably narrow the

    options for root cause.



    That regulator has 'selective ov trip'.

    When an ov condition is detected, the field

    voltage from the regulator MUST be high

    for the ov trip to be triggered. 



    This logic allows more than one alternator

    to parallel on a bus and avoid an ov trip

    for both alternators should only one of them

    mis-behave.  Knowing what I do about the

    hardware, it seems most likely that the ov

    sensing system is being irritated by some

    phenomenon in the system.



    In the early days of crowbar ov system

    development, we were chagrined to discover

    that SOME airplanes had extra-ordinarily

    significant transient sources that would

    nuisance trip our regulators. Regulars

    with years of satisfactory service on

    thousands of airframes. 



    I'm not aware of recent examples of

    'extra ordinary irritation' but I wouldn't

    discount it.



    Can you pair the ov trip even with any particular

    action elsewhere in the system?



 



 

   Bob . . .    [quote][b]

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sat Jun 27, 2015 4:04 am Post subject: Re: Alternator problem?

 	  Quote: 	
		  If we were conducting this investigation in B-31 at Beech (Flight Test) we would get out a data acquisition system... 	


Hey Bob,



Yeah, my kingdom for a DAQ that I could put on this. 



 	  Quote: 	
		  Can you pair the ov trip even with any particular action elsewhere in the system? 	




No. Like I said, the engine runs thus far have all been short (~5 min) and I've been focusing on fuel and temp related indicators.



The engine issues have been resolved so now the engine runs should be longer and I should be able to better monitor the electrical side to identify if there's an event which precedes it or if it's random.



Right now I'm trying to decide if I should pull the alternator or wait and see.



Thanks,

Don

user9253

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

Posted: Sat Jun 27, 2015 4:48 am Post subject: Re: Alternator problem?

 	  Quote: 	
		  As it has been explained to me, the voltage regulator is determining the fault. The VP-X is reporting the fault. 	


Looking at the LR3C documentation, there is no output terminal dedicated to providing an over-voltage warning.  Therefore the only way that the LR3C can indicate over-voltage is by the crowbar circuit shorting out terminal 6.  If terminal 6 gets its power from the VP-X and not from a circuit breaker, then the VP-X should report over-current, not over-voltage.  I do not know how the VP-X works, but expect that it monitors system voltage independently from the LR3C.  

 If the VP-X reports over-voltage, a troubleshooter might ask, is it telling the truth or lying?  What is the over-voltage setpoint?  How long must the voltage be over the setpoint before tripping?  Can the pilot change the over-voltage setpoint?

Joe

_________________
Joe Gores

ceengland7(at)gmail.com
Guest

Posted: Sat Jun 27, 2015 4:54 am Post subject: Alternator problem?

On Sat, Jun 27, 2015 at 7:04 AM, donjohnston <don(at)velocity-xl.com (don(at)velocity-xl.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com (don(at)velocity-xl.com)>

 > If we were conducting this investigation in B-31 at Beech (Flight Test) we would get out a data acquisition system...

 Hey Bob,

 Yeah, my kingdom for a DAQ that I could put on this. 

 > Can you pair the ov trip even with any particular action elsewhere in the system?

 No. Like I said, the engine runs thus far have all been short (~5 min) and I've been focusing on fuel and temp related indicators.

 The engine issues have been resolved so now the engine runs should be longer and I should be able to better monitor the electrical side to identify if there's an event which precedes it or if it's random.

 Right now I'm trying to decide if I should pull the alternator or wait and see.

 Thanks,

 Don

Â 

Pardon my density, but with an externally regulated alternator, how is it possible for the alternator itself to be the cause of overvoltage? Isn't it just a few coils of wire on some iron? It can't produce any significant voltage at all without field current supplied by the regulator, right? It's hard for me to envision any fault within the alternator that would produce *higher* than design voltage. Any short or open circuit inside the alternator should produce either lower or no voltage output, unless I'm missing something.

Charlie

  [quote][b]

user9253

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

Posted: Sat Jun 27, 2015 5:35 am Post subject: Re: Alternator problem?

Good question Charlie.  I also want to know what can go wrong with an externally regulated alternator that would cause over voltage.

Joe

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 27, 2015 6:31 am Post subject: Alternator problem?

At 08:35 AM 6/27/2015, you wrote:

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



 Good question Charlie.  I also want to know what can go wrong with an externally regulated alternator that would cause over voltage.

 Joe



 --------

 Joe Gores 	


   Cogent questions gentlemen. The short answer is,

   it can't.  The long answer is that the transfer

   function of voltage control in some regulators

   doesn't handle brush-bounce well. This can

   COMBINE with poor design of the OV trip system

   to create some vexing symptoms. I can relate a

   first hand-experience with OV trips in brand new

   airplanes that go back over 30 years . . . with

   engineers in three institutions pointing fingers

   at each other while your's truly kept reminding

   them of the obvious. That problem was only

   recently solved by a long recommended replacement

   of a regulator that should not have been qualified

   onto the airplane in the first place.



   If and LR3 is manifesting poor response to

   brush-bounce, this will be a first in my experience.

   It would be the collision of THREE conditions, each

   at the extremes of their production tolerances,

   or perhaps a manufacturing error.



   I think this quite improbable but easy to check

   with the swapping of one of the two waring factions.

   The regulator probably being the easiest. There

   are some peek, poke and ponder exercises to 

   conducted before we play swap-tronics. 



 



 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 27, 2015 6:40 am Post subject: Alternator problem?

At 07:04 AM 6/27/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com>



 

 > If we were conducting this investigation in B-31 at Beech (Flight Test) we would get out a data acquisition system...



 Hey Bob,



 Yeah, my kingdom for a DAQ that I could put on this. 	


   The Force is in sympathy with you. Paul Fisher

   and I will be stirring this into the list of

   things to do . . . as soon as we clear the decks

   of another commitment . . . probably after

   OSH.  The availability of off-the-shelf DAS

   hardware and supporting graphical user

   interface leaves no excuses for not crafting

   a suite of hardware that addresses capabilities

   we've dreamed about here on the List for 20

   years.



   There's no 'hard' work to be done here . . .

   only assemble off the shelf stuff into 

   useful tools. It's all about the packaging.



   By the way, this is not a state secret project.

   If any members on the List have ECB layout

   capabilities and reasonable skills at slinging

   solder, contact me off-list and we'll see how

   your skill-set offer might fit into this

   project.



   I'm contemplating this becoming a tool for

   DIY efforts, perhaps a tool that could be rented

   and shipped around the country as needed, and

   it certainly has possibilities as an article

   for KitPlanes. 



   The time for OBAM aviation to acquire routine

   access to low cost measurement tools arrived a few

   years ago and we were asleep at the keyboard. 



 

 

   Bob . . .    [quote][b]

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sat Jun 27, 2015 7:00 am Post subject: Re: Alternator problem?

I'll try an answer with either what I know or what I've been told:



The VP-X monitors the system voltage.  When it hits 32v, it shuts off the power to the field and reports an overvoltage fault. (see attached)



I don't know exactly where it's monitoring the system voltage.  I would guess at it's connection to the system bus.



The only "adjustment" to the overvoltage trigger level is whether it's installed in a 14v or 28v system. On a 28v system, the OV trigger is hard set at 32v. 



Vertical Power offered to bench check the VP-X.  But since this is early in the game, I was hoping to get some more ideas and data before going down that road.



Speaking of data, I did run across this little guy:

DataQ Instruments DI-149

http://www.dataq.com/products/di-149/index.html?gclid=Cj0KEQjwk7msBRCJj67khY2z_NIBEiQAPTFjv9iqePcOkNiAMApB_amhAfmVZ-fp0KOI3tHOgpWA9VoaAnUa8P8HAQ



I'm wondering if it would be helpful to identify what's happening.

IMG_20150603 (Large)(1).jpg

Description:

Filesize:

233.97 KB

Viewed:

12270 Time(s)

yellowduckduo(at)gmail.co
Guest

Posted: Sat Jun 27, 2015 7:07 am Post subject: Alternator problem?

Instead of impossible, I'd venture 'incredibly unlikely'.  As in more 

probable that I'll be hit by lightning before I send this. However I can 

envision a scenario where a stray bit of internal debris shorts some 

alternator output over to the field coil. Even less likely here where 

the situation appears to be intermittent.

The question was asked but since it is not even worth consideration at 

this point,  I'm going to add

do not archive

Ken

On 27/06/2015 10:29 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   At 08:35 AM 6/27/2015, you wrote:

> 

>

> Good question Charlie.  I also want to know what can go wrong with an 

> externally regulated alternator that would cause over voltage.

> Joe

>

> --------

> Joe Gores

   Cogent questions gentlemen. The short answer is,

   it can't.  The long answer is that the transfer

   function of voltage control in some regulators

   doesn't handle brush-bounce well. This can

   COMBINE with poor design of the OV trip system

   to create some vexing symptoms. I can relate a

   first hand-experience with OV trips in brand new

   airplanes that go back over 30 years . . . with

   engineers in three institutions pointing fingers

   at each other while your's truly kept reminding

   them of the obvious. That problem was only

   recently solved by a long recommended replacement

   of a regulator that should not have been qualified

   onto the airplane in the first place.

   If and LR3 is manifesting poor response to

   brush-bounce, this will be a first in my experience.

   It would be the collision of THREE conditions, each

   at the extremes of their production tolerances,

   or perhaps a manufacturing error.

   I think this quite improbable but easy to check

   with the swapping of one of the two waring factions.

   The regulator probably being the easiest. There

   are some peek, poke and ponder exercises to

   conducted before we play swap-tronics.

   Bob . . .

 *

 *

etienne.phillips(at)gmail
Guest

Posted: Sat Jun 27, 2015 8:06 am Post subject: Alternator problem?

Hi Bob



Have you considered using the Red Pitaya as a base for signal gathering? It's an open source DAQ that already has a lot of the hard work done. It's not dirt cheap ($320) but may offer a quick route to a portable, rentable or EAA chapter own-able device that would fit the bill.

Check out www.redpitaya.comÂ 

Thanks

Etienne

On 27 June 2015 at 16:39, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

[quote]  At 07:04 AM 6/27/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com (don(at)velocity-xl.com)>



 

 > If we were conducting this investigation in B-31 at Beech (Flight Test) we would get out a data acquisition system...



 Hey Bob,



 Yeah, my kingdom for a DAQ that I could put on this. 	


 Â  The Force is in sympathy with you. Paul Fisher

 Â  and I will be stirring this into the list of

 Â  things to do . . . as soon as we clear the decks

 Â  of another commitment . . . probably after

 Â  OSH.Â  The availability of off-the-shelf DAS

 Â  hardware and supporting graphical user

 Â  interface leaves no excuses for not crafting

 Â  a suite of hardware that addresses capabilities

 Â  we've dreamed about here on the List for 20

 Â  years.



 Â  There's no 'hard' work to be done here . . .

 Â  only assemble off the shelf stuff into 

 Â  useful tools. It's all about the packaging.



 Â  By the way, this is not a state secret project.

 Â  If any members on the List have ECB layout

 Â  capabilities and reasonable skills at slinging

 Â  solder, contact me off-list and we'll see how

 Â  your skill-set offer might fit into this

 Â  project.



 Â  I'm contemplating this becoming a tool for

 Â  DIY efforts, perhaps a tool that could be rented

 Â  and shipped around the country as needed, and

 Â  it certainly has possibilities as an article

 Â  for KitPlanes. 



 Â  The time for OBAM aviation to acquire routine

 Â  access to low cost measurement tools arrived a few

 Â  years ago and we were asleep at the keyboard. 



 

 

 Â  Bob . . .     	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




[b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 27, 2015 8:06 am Post subject: Alternator problem?

At 06:34 AM 6/26/2015, you wrote:

 --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com>



 I'm in the process of trying to track down an over voltage fault. 



 So far the engine runs that I've been doing have been relatively short duration (mostly around 5-10min) while I'm getting the engine dialed in. On about 4 occasions I've noticed the alternator circuit has faulted for "over voltage". 



 I'm running a 28v electrical system 

 VP-X Pro

 B&C LR3C voltage regulator

 Kelly Aerospace 50a alternator

 Continental IO-550 engine. 



 Vertical Power and B&C have had me check a number things.  All checks have shown voltage levels, drops and wire resistance to be well within parameters.



 



   How are your LR3 and VPX system configured? The

   LR3 is fitted with crowbar OV protection. If I

   understand your symptoms, it's an OV sense and

   protection function within the VPX that tripping?

   Can you de-program the VPX ov function? Or raise

   it's trip point to some big number? You don't need

   TWO ov protection systems.



 

  	  Quote: 	
		  B&C is recommending to pull the alternator and have it checked. 	


   In the great spaghetti-mix that is aviation

   accessories, marketing and business models,

   it's difficult to keep track of who's alternator

   is being built by whom and with what, if any,

   improvements. 



   The alternators involved in the three-decade saga

   of new airplane OV trips were the occasionally-unfair

   targets of accusatory assertions . . . but they

   DID demonstrate varying degrees of brush-bounce

   that often faded to acceptable levels after the first

   20 hours or so of operation. For a time, brand new

   alternators were being pulled off engines to be

   'broke in' on a test stand before being re-installed.

   A poorly understood work-around for what was a fundamental

   design flaw in the regulator.



   The whole legacy family of gear-driven alternators

   for Continental engines have been the subject

   of numerous 'investigations' . . . to this very day

   . . . in spite of the fact that the car-builders

   put those issues to bed three or four decades ago.

   Such is the plight of consumers deprived of choices

   outside the bounds of the cookie-cutter TC airplane

   business.



   Given what I DO KNOW about that family

   of alternators and what I DO NOT know about the

   VPX OV sense and response philosophy, it may well

   be that your symptoms have root cause in

   conditions not unlike those I've described

   earlier in this thread. The problem may have

   nothing to do with the LR3 and everything to

   do with a discontinuity in assembly of

   simple-ideas that govern performance.



 

  	  Quote: 	
		  I"m just wondering if anyone has run into anything similar with these alternators before I pull it ship it out. 	




   I have seen NO requirements that quantify, put

   limits on or offer diagnosis tools for the detection

   of brush bounce in airplane alternators. I've never

   been able to measure it on the test bench . . .

   the only way I could strengthen the hypothesis that it

   existed was to add a filter to the field terminals of

   the alternator and demonstrating that the problem

   went away.



   The filter only protected the poorly designed 

   ov sense system from a noise that was common to

   and present in most alternators as a matter of

   simple physics . . . noise so small that it was

   difficult to detect amongst the other noises (All

   well within MIL-STD-704 recommendations).



   Just for grins, we could craft a little filter

   assembly to jury-rig to the back of your alternator.

   This experiment is not without risk of the

   various participants 'relaxing' because your

   particular manifestation went away.  If

   brush noise is indeed root to your symptoms,

   it's indication of a fundamental design deficiency

   in the ov sense system . . . NOT THE ALTERNATOR.



 



 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 27, 2015 8:26 am Post subject: Alternator problem?

At 10:06 AM 6/27/2015, you wrote:

 --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com>



 Instead of impossible, I'd venture 'incredibly unlikely'.  As in more probable that I'll be hit by lightning before I send this. However I can envision a scenario where a stray bit of internal debris shorts some alternator output over to the field coil. Even less likely here where the situation appears to be intermittent.

 The question was asked but since it is not even worth consideration at this point,  I'm going to add



  Actually, Mooney experienced just such an event

  back about 1980. I recall peering into the teardown

  of an alternator that should have got some

  combination of craftsmen and inspectors fired.

  

  So it's not totally outside the realm of possibility.

  But yes . . . in this ISO9000 world of 'perfection'

  it should be exceedingly remote.



  I wish I could remember the name of the engineer

  I interacted with at Mooney. A solidly grounded,

  common sense fellow with an airs of personality

  that put a lot of people off. He had a small, red,

  rubber coated steel mallet on which he inscribed

  the non de plume, "PATIENCE".



  I never witness it personally, but he was renowned

  for expressing occasional bouts of frustration

  by abusing the corner of his desk with "Patience".

  Indeed, there were markings in the finish that

  attested to his vice. He proved to be one of my

  most valuable collaborators over those years.



  On numerous occasions since, I have wondered

  if there would be value in acquiring a "Son of

  Patience". On further reflection, pounding on

  a conference room table with a red hammer these

  days would probably get me a visit from a host

  of stern faced folks 'concerned' about my ability

  to integrate in the modern culture.



 

 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jun 27, 2015 8:46 am Post subject: Alternator problem?

At 11:04 AM 6/27/2015, you wrote:

  	  Quote: 	
		  Hi Bob



 Have you considered using the Red Pitaya as a base for signal gathering? It's an open source DAQ that already has a lot of the hard work done. It's not dirt cheap ($320) but may offer a quick route to a portable, rentable or EAA chapter own-able device that would fit the bill.



 Check out www.redpitaya.comÂ 



 Thanks

 Etienne 	


   To be sure, you've discovered one of a host

   of potential possibilities. My current thoughts

   are based on a VERY low cost DAS device I mentioned

   here on the List a few days ago.



  http://tinyurl.com/nvduk9x



   For what ever it may lack in capability, you

   sure can't argue about the price . . . especially

   since it comes with a capable graphical user

   interface and writes data to tabular files

   for analysis with other tools.



   I'm thinking of dropping this device onto a

   'mother board' fitted with, what we'll have to

   deduce, a useful collection of signal conditioners

   for voltage, current, pressure, temperatures, etc.



   Theres a REALLY handy current transducer with

   great accuracy and frequency response  



  http://tinyurl.com/p9fk8po



   The 6A version is easily adapted to sense currents

   from hundreds of milliamps to hundreds of amps. Voltage

   signal conditioning is easy. Temperature is easy in

   the realm of solid state tranducers up to 100C, but

   a channel of K thermocouple data would probably be good

   too. 



   Pressure 4-20 mA pressure transducers are COTS

   items.



   I've got $hundreds$ in DAS equipment on the

   shelf that I've used to great advantage in the

   TC world . . . but too complex to install/operate/

   resolve in the OBAM world.  This is an exercise

   in extracting lab grade data from a KISS box.

   Need to make this so $low$ and simple that fewer

   folk in the OBAM market are put off by the expense

   risk and willing to try it for themselves.



   This is the rolling-stock-consist for a train of ideas in 

   the current pot of idea-stew. I'm 'seeing' a board

   about 2.5 x 3.5 inches that would mount the pic-stick

   and 5-8 channels of signal conditioning for a BOM cost on

   the order of $50-60.



 

   Bob . . .    [quote][b]

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sat Jun 27, 2015 11:10 am Post subject: Re: Alternator problem?

 	  nuckolls.bob(at)aeroelect wrote: 	
		  

   In the great spaghetti-mix that is aviation

   accessories, marketing and business models,

   it's difficult to keep track of who's alternator

   is being built by whom and with what, if any,

   improvements. 	




All I can say with certainty is that the P/N of the alternator is 646843.  According to what I've been able to determine it's a TCM 60a alternator.  I was told that line of business was sold to Kelly Aerospace. 



 	  Quote: 	
		   The alternators involved in the three-decade saga of new airplane OV trips were the occasionally-unfair targets of accusatory assertions . . . but they DID demonstrate varying degrees of brush-bounce that often faded to acceptable levels after the first 20 hours or so of operation. 	


You just went over my head with "brush-bounce". 



 	  Quote: 	
		  Given what I DO KNOW about that family of alternators and what I DO NOT know about the VPX OV sense and response philosophy, it may well be that your symptoms have root cause in conditions not unlike those I've described  earlier in this thread. The problem may have nothing to do with the LR3 and everything to do with a discontinuity in assembly of simple-ideas that govern performance. 	


If this means that it's possible that I did something wrong putting this system together, there is absolutely no doubt about that!  

If so, can you give me some idea of where I may have a disconnection in the  "discontinuity in assembly of simple-ideas that govern performance"



 	  Quote: 	
		  Just for grins, we could craft a little filter assembly to jury-rig to the back of your alternator. This experiment is not without risk of the various participants 'relaxing' because your particular manifestation went away.  If brush noise is indeed root to your symptoms, it's indication of a fundamental design deficiency in the ov sense system . . . NOT THE ALTERNATOR. 	




I'm all for grins! Can you give me an idea where to get or how to build this filter?

user9253

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

Posted: Sat Jun 27, 2015 3:40 pm Post subject: Re: Alternator problem?

Directions for making a filter:

http://www.sanantoniohams.org/tips/whine.htm

 	  Quote: 	
		  You just went over my head with "brush-bounce". 	
Alternators have bushes that ride on slip rings.  If the rings are not concentric, the brushes will move up and down in their holders.



 	  Quote: 	
		  can you give me some idea of where I may have a disconnection in the "discontinuity in assembly of simple-ideas that govern performance 	
I get the impression that Bob is inferring that he does not trust the VP-X.



I suggest that instead of pulling the alternator, that you replace the voltage regulator with a generic Ford VR166 or equivalent.  There is a list in Bob's book.  The over-voltage and low voltage features of the LR3 are not needed in your application if the VP-X provides over-voltage and the EFIS gives low voltage warning.

Joe

_________________
Joe Gores

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