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nuckollsr(at)cox.net
Guest

Posted: Wed Aug 23, 2006 7:17 am Post subject: MOV's

At 07:07 AM 8/23/2006 -0700, you wrote:



 	  Quote: 	
		  



Bob I love 99% of your posts. You are doing a great job in helping people 

understand and wire their aircraft and based on my limited accident 

investigation of auto engine powered aircraft.



I would guess you have saved hundreds of lives in the past 10 years.



The stupid things people do that do not know of your information is 

astounding.


	


   Thank you for the kind words . . .

 	  Quote: 	
		  However what I was asking for is independent backup of your conclusions as 

my background and experience as well as all the data I can find support my 

opinion not yours.


	


   I'm only asking for independent review (yours) of what I've

   offered based on your perceptions of the physics and NOT

   upon a dump from industry's promotional literature.

 	  Quote: 	
		  What is wrong with asking for independent backup. EVERY source (several 

beyond what has been mentioned recently) I can find that really evaluates 

(and stacks) the different suppression methods put the simple diode at the 

bottom and the bi-directional transorb (or its equivalent) at the top. 

Sure the different approaches are "application dependent" as which work 

better and which are not as good. My point is the transorb always is good 

(and at the top of the lost) so why not use it. No need to retrofit and 

replace diodes IF you were to go on and discuss the cases where the diode 

was not as good.



The only published paper that disagrees with me comes from you. How about 

an industry recognized paper that supports your position? Teachers must be 

able to backup what they say with independent references or the student 

can waver about that and anything else the teacher says. The "prove me 

wrong" is interesting but not useful as most students have no ability to try.


	


   I am NOT disagreeing with you in that the zener-diode technique certainly

   works 100% of the time. The entire thrust of my posting was to dispel any

   notions that folks who choose to use the lowly diode are at-risk for reduced

   relay and contactor life. It's just that simple sir. I'm mystified as to

   why you get wrapped around the good-better-best axle when those terms

   are non-quantified and not even offered in the context of exactly HOW one

   technique excels.



   You're fond of citing lots of literature while I prefer to make measurements

   and explore for myself the value/hazards of any technique being discussed.

   I've offered my experimental results for the purpose of soliciting

   considered critical review to either support or refute a hypothesis.

   I chose this technique because literature without supporting experimental

   data proves nothing while the repeatable experiment offered for

   critical review illuminates the path for success.

 	  Quote: 	
		  I have no interest in trying to prove what the industry says in unison. I 

did see the proving data in the EMI lab when I worked in aerospace that 

supported the industry and we simply proceeded on. Why not?, there was no 

significant mechanical, electrical or cost difference and in some cases 

there was a functional improvement. Sure 90% of the time a diode was just 

fine but in the other cases it was not.


	


   . . . agreed . . . and I'm only suggesting that the 10% of cases

   were the simple diode is found lacking do not occur in the OBAM

   aircraft.

 	  Quote: 	
		  I can and have been a teacher but you want to be a teacher and yet get 

upset when the student says "prove it".


	


   Nobody, repeat NOBODY upsets me over a discussion of

   facts and physics. Your the only person on this list who

   has succeeded in upsetting me when you alluded to a cadre

   of unhappy customers of my products who according to you

   were so intimidated by my aura that they would not return

   their purchases for a full refund.



   I could only assume that you had chosen to insert yourself

   into what was intended to be an honorable supplier/consumer

   relationship. That DID upset me.



   I will confess to some frustration when data and test

   techniques offered to support a hypothesis produces a

   literature storm of information not specific to discussion

   of the hypothesis.



 	  Quote: 	
		    Using only your position (which differs from industry) is not enough for 

 me (and some others unwilling to post)

  given the predictable results. A test by you of a single case or a 

 couple of cases does

  not make the statement universally true in all cases.


	


   My position differs not a whit from industry when it comes to

   making measurements and deducing performance or lack thereof

   based on those measurements. But like laundry soap, cars, and

   mouthwash, the promotional literature (including much of the

   applications notes) are not written with good science and understanding

   as goals. For example: I'm about ready to publish a detailed review of

   the data sheet for the MC33092 internal regulator where

   I will show that in spite of the product's modern integrated

   circuit manufacturing with a whole fist full of transistors,

   the manner in which it is used in alternators prevents

   exploitation of its special features. In practice, it

   performs no better than the two-transistor regulators we

   were installing on Cessnas 40 years ago.



   By your logic I could consider assembling a house with

   titanium nails and be 100% assured of future performance.

   When the astute system designer compares REQUIREMENTS with

   techniques and materials capable of meeting requirements,

   the competitive and successful product may very well NOT use

   titanium nails.



   Words here on the list have recommended that builders rip out

   all their diodes and replace them with a more expensive product

   and promoted by the notion that doing so has cost-of-ownership

   value for having made the switch.



   I am only suggesting that the notion is pure marketing hype

   and not supported by any experiments I've conducted to explore

   the potential benefits. I was not arguing any good-better-best,

   only against the notion that the product being offered produces

   a demonstrable return on investment. In this case a plain ol'

   cement coated box nail does the job. If someone chooses to use

   the titanium nail cause he has the time and doesn't mind the

   expense, fine. But I object to marketing the titanium nail with

   the use of unsupported assertions designed to instill worries

   on the part of the potential neophyte customer.



   There's that honorable consumer/supplier relationship thing

   again.



   Bob . . .

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paulm(at)olypen.com
Guest

Posted: Wed Aug 23, 2006 9:00 am Post subject: MOV's

I have long ago given up trying to challenge every industry position. I do 

not have the time or interest to do so. When I do run across something in a 

design that is not consistent with the industry I do, and have investigated 

just what is different.



The industry papers of the time were from relay manufacturers who had no 

reason to support one suppressor method or the other as they did not sell 

suppressors of any type (at the time) Their interest appeared to be to show 

how to get the most reliable use of their products which ranged from very 

small relays to huge ones and thus the recommendations were designed to be 

general and not always apply to any specific case.



In the case of transorbs; many years ago I noted that a designer had used a 

diode and there were unwanted noise introduced into the system. It was 

determined that the opening delay and more important showed start to finish 

contact opening time was part of the problem. At that time I want into the 

EMI lab and with expert help we determined that part of the required fix was 

to quicken the opening contact time (not the delayed start of opening but 

the duration of contact opening).



PART of the solution was replacing the Diode with a Transorb. There was more 

required that evolved contact arc suppression.



The general conclusion was an across the board replacement of diodes with 

transorbs as it did not hurt and in rare cases prevent problems. No retrofit 

was made just new design used transorbs.



I agree that your documented test of a small relay showed no significant 

time of contact opening but that is not necessarily so with power contactors 

seen in aircraft.



Now in the case of experimental aircraft I have discovered one case the "B" 

lead contactor can require a transorb as a partial solution to contact 

arcing and continued arcing in one failure mode of the alternator.



I only intended to point out that case not make a big deal of it. BTW I am 

not the only you have gotten up set with but perhaps the most memorable.



Paul

---

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nuckollsr(at)cox.net
Guest

Posted: Thu Aug 24, 2006 6:46 am Post subject: MOV's

At 10:03 AM 8/23/2006 -0700, you wrote:



 	  Quote: 	
		  



I have long ago given up trying to challenge every industry position. I do 

not have the time or interest to do so. When I do run across something in 

a design that is not consistent with the industry I do, and have 

investigated just what is different.


	


   I don't think I suggested it. Obviously, industry

   publishes a great deal of data that is need for

   the make/buy/ignore decision along with information

   vital to integrating a device into a new design.



   Challenges are warranted when words taken from

   what appears to be well grounded, widely distributed

   ideas that cause readers to invest both $time$

   and emotional capital for adoption of some product

   or idea.



   It's incumbent upon the astute designer (and advisor)

   to evaluate and understand the return on investment. It's

   not so much a challenge as it is a quest for understanding.

   The unfortunate condition is that potential customers

   are oft encouraged to spend $time$ on a product or activity

   that fails to deliver . . . or delivers a feature that's

   not really useful.

 	  Quote: 	
		  The industry papers of the time were from relay manufacturers who had no 

reason to support one suppressor method or the other as they did not sell 

suppressors of any type (at the time) Their interest appeared to be to 

show how to get the most reliable use of their products which ranged from 

very small relays to huge ones and thus the recommendations were designed 

to be general and not always apply to any specific case.


	


    Yup . . . the universe is long on generalized recipes

    for success but it's not uncommon that such recipes are

    short on detailed explanations for applicability and

    return on investment . . .

 	  Quote: 	
		  In the case of transorbs; many years ago I noted that a designer had used 

a diode and there were unwanted noise introduced into the system. It was 

determined that the opening delay and more important showed start to 

finish contact opening time was part of the problem. At that time I want 

into the EMI lab and with expert help we determined that part of the 

required fix was to quicken the opening contact time (not the delayed 

start of opening but the duration of contact opening).



PART of the solution was replacing the Diode with a Transorb. There was 

more required that evolved contact arc suppression.



The general conclusion was an across the board replacement of diodes with 

transorbs as it did not hurt and in rare cases prevent problems. No 

retrofit was made just new design used transorbs.



I agree that your documented test of a small relay showed no significant 

time of contact opening but that is not necessarily so with power 

contactors seen in aircraft.


	


    I tested battery contactors too.



    Your decisions to take some action based on data

    acquired during an investigation cannot be faulted

    or argued with. At the same time, recommendation of

    broad prescriptions for applying a design technique

    because it mitigated a problem so specific as to

    required detailed investigation is not good science

    or business.

 	  Quote: 	
		  Now in the case of experimental aircraft I have discovered one case the 

"B" lead contactor can require a transorb as a partial solution to contact 

arcing and continued arcing in one failure mode of the alternator.


	


    Yup, but that's a new situation arising from an especially

    antagonistic load switched by the contactor. Here the load

    is not inductive, resistive, or lamp . . . it's an engine

    driven energy source with dynamics that were never considered

    when all the coil suppression techniques were crafted and

    described in the oft cited documents. I.e., those documents

    have almost no significance for solving the problem.

 	  Quote: 	
		  I only intended to point out that case not make a big deal of it.


	


    I wasn't making a big deal out of it either. My offering

    was in response to recommendations were made based on

    no better data than one gets for choosing laundry

    soap because it says "new and improved" on the box.

 	  Quote: 	
		    BTW I am not the only you have gotten up set with but perhaps the most 

 memorable.


	


    Really? Perhaps I need to be more skilled with the

    use of emoticons . . . Folks often misinterpret my state

    of being. When I am really upset about something, I'll

    make it known. When someone offers an opinion about

    things I've said or done, the input falls in one of

    two categories (1) it's a valid observation worthy of

    consideration and modification of future action - i.e.

    good critical review -OR- (2) "noise" that contains

    no data and should be ignored so that attention to

    simple-ideas is not distracted or diluted. It's relatively

    easy to make that determination without emotional

    investment. But I've readily admitted to being really

    wound up when individuals insert themselves between me and

    my customers such that I am deprived of the opportunity

    to keep them satisfied with their decision to use my

    products and services.



    Bob . . .

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nuckollsr(at)cox.net
Guest

Posted: Thu Aug 24, 2006 6:51 am Post subject: MOV's

At 07:47 AM 8/23/2006 -0700, you wrote:



 	  Quote: 	
		  



Yes I remember that interchange and its a wonderful example how selective 

cut and paste can change what I was saying and its context.



Its a masterpiece.



Paul


	


   Really? There was no intention on my part to distort

   any meaning in your words. If there was distortion,

   it was accidental. I'd be pleased to supply you the

   original for any editing you might wish to do that

   would clarify of your intent.



   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       >

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

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paulm(at)olypen.com
Guest

Posted: Thu Aug 24, 2006 8:34 am Post subject: MOV's

couple of snips

---

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paulm(at)olypen.com
Guest

Posted: Thu Aug 24, 2006 8:34 am Post subject: MOV's

Its history and best left alone.



Paul



---

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