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Alternator mistake

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frank.hinde(at)hp.com
Guest

Posted: Sun Jan 28, 2007 6:54 am Post subject: Alternator mistake

Thought it might be useful to document my rather silly (bonehead

stupid) error I made in installng my alt.



First off I bought an "Autozone special" for an electrically dependant

IFR airplane....It appeared to be functioning OK for a while but clearly

IFR is serious business but I really had not put the level of care

required when selecting the alt.



So I decided to replace with a plane power unit ( I plmbed it into my

existing B lead contctor with OV trip)



About that time the GNS 430  started acting up with a bunch of

unconnected errors. This usually means one thing..Bad grounding. But

what could it be? I had a bullet proof "forrest of tabs" ground block

and dual path grounds.



Turns out as I was removing the old alt from the engine I saw it...I had

painted the bracket to prevent corrosion and I believe the alt could not

get a good ground connection to the engine block. 



The new plane power unit has CAD plated hardware and I also added a

smear of "malaax" (conductive grease used on household electrical cables

from Home Depot etc) to prevent corrosion and ensure a good connection.



The alt must have a good connection to the engine block in order to

provide a stabilised voltage.



Personally I'm amazed I missed the error during install, I could have

simply added a grounding strap between the alt and the engine block too.

Of couse it may have been the old alt was breaking down but I am pleased

to report my instruments are now behaving perfectly...



Frank 7a, halfway thru IFR training...I hope!

nuckollsr(at)cox.net
Guest

Posted: Sun Jan 28, 2007 8:27 am Post subject: Alternator mistake

At 08:54 AM 1/28/2007 -0600, you wrote:

 	  Quote: 	
		  

<frank.hinde(at)hp.com>



  Thought it might be useful to document my rather silly (bonehead

stupid) error I made in installng my alt.



First off I bought an "Autozone special" for an electrically dependant

IFR airplane....It appeared to be functioning OK for a while but clearly

IFR is serious business but I really had not put the level of care

required when selecting the alt.



So I decided to replace with a plane power unit ( I plmbed it into my

existing B lead contctor with OV trip)



About that time the GNS 430  started acting up with a bunch of

unconnected errors. This usually means one thing..Bad grounding. But

what could it be? I had a bullet proof "forrest of tabs" ground block

and dual path grounds.



Turns out as I was removing the old alt from the engine I saw it...I had

painted the bracket to prevent corrosion and I believe the alt could not

get a good ground connection to the engine block.



The new plane power unit has CAD plated hardware and I also added a

smear of "malaax" (conductive grease used on household electrical cables

from Home Depot etc) to prevent corrosion and ensure a good connection.



The alt must have a good connection to the engine block in order to

provide a stabilised voltage.



Personally I'm amazed I missed the error during install, I could have

simply added a grounding strap between the alt and the engine block too.

Of couse it may have been the old alt was breaking down but I am pleased

to report my instruments are now behaving perfectly...


	




    Good data sir! Thank you. Some of you may recall some

    conversations about voltage regulator stability as

    it relates to shared pathways for both sensing the

    voltage to be controlled and OTHER duties like supplying

    field current . . . and in this case conducting output

    current to the crankcase and ultimately electrical system

    ground.



    Even small resistances carrying significant currents

    produce voltage drops in accordance with Mr. Ohm's

    famous E=IR. When E is large with respect to the regulator's

    ability to sense and react to changes in bus voltage,

    the extraneous voltage signals become a form of "noise"

    in voltage regulator's control loop.



    Frank's experiences, investigation and subsequent conclusions

    go right to this point of system performance. I'll make

    a note to include some words about alternator case bonding

    which was only mildly important for ER alternators but

    exceedingly important for achieving advertised performance

    from IR alternators.



    Incidentally Frank, which model of PP alternator did you

    install? Would you be willing to copy/scan the installation

    data that comes with it and send it to me? I note that

    some models on their website speaks of ov votlage protection

    and they've even used the (ugh!) word "crowabar" in the

    context of speaking about ov protection. The photo at



http://www.plane-power.com/images/AL12_EI70%20Wiring.pdf



    shows what appears to be an add-on to the back of their

    product for the purpose of providing OV protection.

    I'm curious as to whether or not you can turn the alternator

    OFF by way of the "field switch" after it has once been

    turned ON.

        Bob . . .



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

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

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

gcomfo(at)tc3net.com
Guest

Posted: Sun Jan 28, 2007 10:46 am Post subject: Alternator mistake

--

nuckollsr(at)cox.net
Guest

Posted: Sun Jan 28, 2007 5:11 pm Post subject: Alternator mistake

At 01:45 PM 1/28/2007 -0500, you wrote:

 	  Quote: 	
		  

     Bob:  Plane Power have advised me verbally that the alternator can be

shut down by way of the "field" switch but their installation drawing is

quite primative and I cannot be sure from it whether or not what they say is

true.  It will be a while before I run the engine but my intent is to check

that function when I do run it.  The module on the rear is described as a

crowbar OV control.  I'm actually working on the -8 again.  My word.



Gordon Comfort

N363GC


	


   Looking forward to getting your report. So all that 'stuff'

   you put in the -4 is making it too crowded? I envy you sir,

   I think the -8 is my personal favorite.



   Bob . . .



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

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

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

frank.hinde(at)hp.com
Guest

Posted: Sun Jan 28, 2007 8:40 pm Post subject: Alternator mistake

Hello Bob,



I installed the smaller 60Amp unit than the one shown in the link you

provided, Not sure what form factor it is but it is considerably smaller

than the 70A unit shown (which incidently looks identical to the ND

Toyota Camry unit I replaced). The reason I fitted this one was that was

all that Van's had in stock and should be big enough even with the dual

electric fuel pump/IFR installation in my airplane.



I do note the voltage regulator is set a little low at around 13.7V.



The crowbar unit on the back appears to just have small single wire that

presumably just collapses the field current. To be honest I was little

reluctant to rely on this device so I wired it in series with my

existing OV protection the basis of which is one of Eric's big

contactors.



Can you turn the unit off?...Hmm, well the instructions do not

specifically mention this. They do say you can turn the unit ON by

energising the filed but I did not see that you could turn it

off...Personally I would not try to do this unless it was an emergency.



I'll have a look in the hangar for the instructions, I do know they were

pretty sparse electriclly speaking.



Incidently different topic, the backup SD-8 alternator cranks out quite

a bit more than 8amps...I can reliably run almost evrything in the

airplane...i.e one FI electric fuel pump, GNS430 and an audio

panel...The battery volts will dip below 12v on a transmit but apart

from that it is enough to drive home if don't use any lights. I would

say the unit makes nearer 12A.



Frank





    Incidentally Frank, which model of PP alternator did you

    install? Would you be willing to copy/scan the installation

    data that comes with it and send it to me? I note that

    some models on their website speaks of ov votlage protection

    and they've even used the (ugh!) word "crowabar" in the

    context of speaking about ov protection. The photo at



http://www.plane-power.com/images/AL12_EI70%20Wiring.pdf



    shows what appears to be an add-on to the back of their

    product for the purpose of providing OV protection.

    I'm curious as to whether or not you can turn the alternator

    OFF by way of the "field switch" after it has once been

    turned ON.

        Bob . . .



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

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

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

klehman(at)albedo.net
Guest

Posted: Mon Jan 29, 2007 5:38 am Post subject: Alternator mistake

If the OV shutdown is simply a crowbar on the IGN terminal that pretty 

much means that I would not trust it either.  Better than nothing maybe 

but...  Can you confirm where that wire goes Frank?

Ken



Hinde, Frank George (Corvallis) wrote:



 	  Quote: 	
		  



 



Hello Bob,



I installed the smaller 60Amp unit than the one shown in the link you

provided, Not sure what form factor it is but it is considerably smaller

than the 70A unit shown (which incidently looks identical to the ND

Toyota Camry unit I replaced). The reason I fitted this one was that was

all that Van's had in stock and should be big enough even with the dual

electric fuel pump/IFR installation in my airplane.



I do note the voltage regulator is set a little low at around 13.7V.



The crowbar unit on the back appears to just have small single wire that

presumably just collapses the field current. To be honest I was little

reluctant to rely on this device so I wired it in series with my

existing OV protection the basis of which is one of Eric's big

contactors.



Can you turn the unit off?...Hmm, well the instructions do not

specifically mention this. They do say you can turn the unit ON by

energising the filed but I did not see that you could turn it

off...Personally I would not try to do this unless it was an emergency.



I'll have a look in the hangar for the instructions, I do know they were

pretty sparse electriclly speaking.



Incidently different topic, the backup SD-8 alternator cranks out quite

a bit more than 8amps...I can reliably run almost evrything in the

airplane...i.e one FI electric fuel pump, GNS430 and an audio

panel...The battery volts will dip below 12v on a transmit but apart

from that it is enough to drive home if don't use any lights. I would

say the unit makes nearer 12A.



Frank





    Incidentally Frank, which model of PP alternator did you

    install? Would you be willing to copy/scan the installation

    data that comes with it and send it to me? I note that

    some models on their website speaks of ov votlage protection

    and they've even used the (ugh!) word "crowabar" in the

    context of speaking about ov protection. The photo at



http://www.plane-power.com/images/AL12_EI70%20Wiring.pdf



    shows what appears to be an add-on to the back of their

    product for the purpose of providing OV protection.

    I'm curious as to whether or not you can turn the alternator

    OFF by way of the "field switch" after it has once been

    turned ON.

        Bob . . .

nuckollsr(at)cox.net
Guest

Posted: Mon Jan 29, 2007 6:16 am Post subject: Alternator mistake

At 10:39 PM 1/28/2007 -0600, you wrote:

 	  Quote: 	
		  

<frank.hinde(at)hp.com>



Hello Bob,



I installed the smaller 60Amp unit than the one shown in the link you

provided, Not sure what form factor it is but it is considerably smaller

than the 70A unit shown (which incidently looks identical to the ND

Toyota Camry unit I replaced). The reason I fitted this one was that was

all that Van's had in stock and should be big enough even with the dual

electric fuel pump/IFR installation in my airplane.



I do note the voltage regulator is set a little low at around 13.7V.


	


    That's disappointing. 13.7 will EVENTUALLY replenish the charge

    in a SVLA battery but the recharge time to 99% of capacity can

    be 3-10x longer than at 14.2 or even 14.6 volts.



    Their website is remarkably silent on the topic of voltage

    setpoints for both OBAM aviation and TC aviation products.

    Nonetheless, if they've been granted permission to install

    on TC aircraft, they're no doubt in possession of data which

    describes the voltage regulation characteristics of their

    PMA products . . . I would expect the OBAM aviation products

    to be identical.



    Drop them a note and ask. You're a $paying$ customer. It's

    not an unreasonable question.

 	  Quote: 	
		  The crowbar unit on the back appears to just have small single wire that

presumably just collapses the field current. To be honest I was little

reluctant to rely on this device so I wired it in series with my

existing OV protection the basis of which is one of Eric's big

contactors.



Can you turn the unit off?...Hmm, well the instructions do not

specifically mention this. They do say you can turn the unit ON by

energising the filed but I did not see that you could turn it

off...Personally I would not try to do this unless it was an emergency.


	


    Unless there's a b-lead disconnection device like that shown

    in Figure Z-24 and Z-24a, there is no risk to the alternator

    to attempt a shutdown via the "ALT FIELD" switch. If this

    switch functions as we've come to expect from traditional

    installations, the alternator will simply stop producing power

    and resume when it's closed. This test can be accomplished at

    low rpm, everything turned off and by watching the voltmeter

    to wiggle when the switch is operated.

 	  Quote: 	
		  I'll have a look in the hangar for the instructions, I do know they were

pretty sparse electriclly speaking.


	


    Thank you for sharing this information. I've written Steve Klodd,

    head chef at Plane Power to inquire about the functionality of

    product features cited on his website. We shall see . . .

 	  Quote: 	
		  Incidently different topic, the backup SD-8 alternator cranks out quite

a bit more than 8amps...I can reliably run almost evrything in the

airplane...i.e one FI electric fuel pump, GNS430 and an audio

panel...The battery volts will dip below 12v on a transmit but apart

from that it is enough to drive home if don't use any lights. I would

say the unit makes nearer 12A.


	


    Also interesting. I've often thought that the capabilities of

    the SD-8 would drift upward with time. The availability of

    high-performance magnets continues to improve and I've always

    thought that the magnet assemblies shipped to B&C might just

    become better with technological age. You may well be

    experiencing this phenomenon.  I'll ask Tim about it the next

    time we talk.



    Bob . . .

frank.hinde(at)hp.com
Guest

Posted: Mon Jan 29, 2007 8:16 am Post subject: Alternator mistake

Hard to tell Ken but it is a very small wire that appears to go to the

center of the machine so my assumption is that it goes directly to one

of the slip ring brushes, the other end is bolted presumably to a

contact that goes to the opposite brush or maybe the case...I'm thinking

it shorts out (or grounds) the field coil.



I'm definatly not an electrical expert so I may well be a little off

here.



Frank



--

klehman(at)albedo.net
Guest

Posted: Mon Jan 29, 2007 9:20 am Post subject: Alternator mistake

You are arousing my curiousity for sure though. If it bypasses the 

silicon and crowbars directly to the field windings, that would make it 

a totally acceptable one time OV protection in my mind. I think that 

would be as good or better than I  have with Z-24 if it limits 

alternator damage to the voltage regulator. More money than my locally 

obtained alternator but easier to install. One nice thing about Z-24 is 

that I can test the OV function with the engine off without damaging 

anything.



I am looking forward to Bob's AEC9004 for a universal solution though. 

If he can demonstrate stalling alternators without damaging them that 

would be marvelous.



Ken



Hinde, Frank George (Corvallis) wrote:



[quote]



Hard to tell Ken but it is a very small wire that appears to go to the

center of the machine so my assumption is that it goes directly to one

of the slip ring brushes, the other end is bolted presumably to a

contact that goes to the opposite brush or maybe the case...I'm thinking

it shorts out (or grounds) the field coil.



I'm definatly not an electrical expert so I may well be a little off

here.



Frank



--

frank.hinde(at)hp.com
Guest

Posted: Mon Jan 29, 2007 10:03 am Post subject: Alternator mistake

Ya, for me I have come to regard the $400 alternator as almost

sacrificial, as long as it does not fry my $6000 GNS 430!..>And

especially as long as it doesn't do it when I need it in hard IMC.



It seems alternators have very low failure rates generally (and I have

an SD8 backup) then a resettable alternator is a pretty low priority for

me...Would I fly 500 miles home on an SD8 backup in IFR? Probably not,

but I might wait a day and do it VFR then send the alt away for repair

upon my return home. 



My second error (apart from the grounding thing) was using a cheap

rebuild for what has become a critical application (I'm doing my IFR

training in the RV7a). The fact it took me about a day to fabricate all

the brackets, source a suitable belt etc and $400 is looking pretty

inexpensive...



Anyway some rambling thoughts



Frank



--

nuckollsr(at)cox.net
Guest

Posted: Mon Jan 29, 2007 11:24 am Post subject: Alternator mistake

At 11:59 AM 1/29/2007 -0600, you wrote:

 	  Quote: 	
		  

<frank.hinde(at)hp.com>


	


   <SNIP>

 	  Quote: 	
		  My second error (apart from the grounding thing) was using a cheap

rebuild for what has become a critical application (I'm doing my IFR

training in the RV7a). The fact it took me about a day to fabricate all

the brackets, source a suitable belt etc and $400 is looking pretty

inexpensive...



Anyway some rambling thoughts


	


   Not rambling thoughts but critical design review.

   I don't know how many builders have written or called

   about sources for materials to accomplish some portion

   of their project DIY. I always try to ask, "Are you

   doing this because you WANT to learn how it's done

   and enjoy doing it for the experience . . . or is it

   to save money."



   More often than not, the answer is, "to save money".

   I've come to realize that our rudimentary commodity

   of exchange is $time$ . . . and when one considers

   the total cost of acquisition and ownership in terms

   of total $time$, they quite often find that it would

   have been better to spend their $time$ acquiring

   cash at something they're good at than to spend more

   $time$ in an attempt to get something new done right

   the first time.



 	  Quote: 	
		  You are arousing my curiousity for sure though. If it bypasses the

silicon and crowbars directly to the field windings, that would make it

a totally acceptable one time OV protection in my mind. I think that

would be as good or better than I  have with Z-24 if it limits

alternator damage to the voltage regulator. More money than my locally

obtained alternator but easier to install. One nice thing about Z-24 is

that I can test the OV function with the engine off without damaging

anything.


	


   You can test Z-24 with the engine running. Just run at

   ramp rpm and wait until the battery is recharged after

   cranking the engine. The magnitude of the load dump

   transient is a function of alternator output current

   and rpm at the time the b-lead opens.  A lightly

   stressed alternator doesn't "bump" vigorously.



   Note on page 2 of



http://www.aeroelectric.com/Mfgr_Data/Semiconductors/MC33092A.pdf



   . . . the regulator is spec'd to stand off a load dump

   transient of 40v for 125 mS.  I think this is typical

   of the industry and mirrors DO-160 recommendations

   for 14v systems.



        Bob . . .



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

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

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

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