Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Spike catcher diode

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

wroe1(at)dbtech.net
Guest

Posted: Fri Jul 03, 2009 8:12 am Post subject: Spike catcher diode

I have the stock Van’s master and starter contactors.  Does anyone know if either of these items have internal diodes?  Also, what size diode should be used on the starter contactor assuming an external is needed?  I’m referencing AEC Z-13/8.  Thanks!  

     

Wade  Roe  

   

SOUTHERN CARBIDE TECHNOLOGIES, INC.  

7739 Unity Road M&D Industrial Park  

Tuscaloosa, AL  35401  

   

205-248-6700  

205-248-6372 fax  

  

   

       [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jul 03, 2009 10:33 am Post subject: Spike catcher diode

At 11:09 AM 7/3/2009, you wrote:

  	  Quote: 	
		   I have the stock Van’s master and starter contactors.  Does anyone know if either of these items have internal diodes?  Also, what size diode should be used on the starter contactor assuming an external is needed?  I’m referencing AEC Z-13/8.  Thanks! 	


   The master certainly would not. The starter MIGHT

   and would say so stamped on the under side of

   the mounting flange. In any case, two suppressors

   are better than no suppressors.



   There are no rectifier diodes you can pick that

   will be at-risk for electrical overload. My personal

   favorites are the electrical over-kill (but 

   mechanically robust) 1N540x series. These

   are really inexpensive and available from

   Radio Shack and others . . .



  http://aeroelectric.com/Pictures/Misc/RS_Diodes.jpg



   The 1A, 1N400x series are electrically quite

   adequate but more fragile.



 

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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



     [quote][b]

wroe1(at)dbtech.net
Guest

Posted: Tue Jul 07, 2009 8:16 am Post subject: Spike catcher diode

On the stock Van’s battery contactor, there is only three terminals (two 5 1/6 and one 3/16 front and center).  I am unsure where to install the IN5400 diode.  Can anyone comment on proper placement?  Also, what about the diode placement on the Van’s stock starter contactor?  Please excuse my very “green” hands regarding electronics…learning!  

   

Thanks!   

     

Wade  Roe  

   

EAA 557  

Aeronca 7AC flying  

RV-7 nearing completion  

   

  

--

bob(at)bob-white.com
Guest

Posted: Tue Jul 07, 2009 8:55 am Post subject: Spike catcher diode

Hi Wade,



You need to put the diode directly across the coil with the cathode

(the end marked with a stripe) connected to +12V.  On a three terminal

contactor, +12V is on the terminal connected to the battery.  Then

connect the anode to the small terminal used to actuate the relay.

Attached drawings lifted out of one of Bob's publications.



On Tue, 7 Jul 2009 10:53:39 -0500

"Wade Roe" <wroe1(at)dbtech.net> wrote:



[quote] On the stock Van's battery contactor, there is only three terminals (two

 5 1/6 and one 3/16 front and center).  I am unsure where to install the

 IN5400 diode.  Can anyone comment on proper placement?  Also, what about

 the diode placement on the Van's stock starter contactor?  Please excuse

 my very "green" hands regarding electronics.learning!

  

 Thanks! 

  

 Wade Roe

  

 EAA 557

 Aeronca 7AC flying

 RV-7 nearing completion

  

 --

contactors.jpg

Description:

Filesize:

23.44 KB

Viewed:

13027 Time(s)

rv(at)thelefflers.com
Guest

Posted: Tue Jul 07, 2009 8:56 am Post subject: Spike catcher diode

Vertical Power has a nice document explaining contactor wiring.  

   

http://www.verticalpower.com/docs/Contactor_Wiring.pdf   

   

bob  

   

       

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Wade Roe

 Sent: Tuesday, July 07, 2009 11:54 AM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: Spike catcher diode   

  

  

   

On the stock Van’s battery contactor, there is only three terminals (two 5 1/6 and one 3/16 front and center).  I am unsure where to install the IN5400 diode.  Can anyone comment on proper placement?  Also, what about the diode placement on the Van’s stock starter contactor?  Please excuse my very “green” hands regarding electronics…learning!  

   

Thanks!   

     

Wade Roe  

   

EAA 557  

Aeronca 7AC flying  

RV-7 nearing completion  

   

  

--

wroe1(at)dbtech.net
Guest

Posted: Tue Jul 07, 2009 9:58 am Post subject: Spike catcher diode

Thanks for the comments.  The Vertical Power doc. is nicely done.  

     

Wade  Roe  

   

EAA 557  

Aeronca 7AC flying  

RV-7 nearing completion  

   

   

  

--

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Wed Jul 08, 2009 6:13 am Post subject: Re: Spike catcher diode

This issue has been argued here for years, so spare me your flames Bob.



Today, no electronic engineer recommends diodes for contactor coil suppression. They are not the best, nor the second, nor the third, nor even fourth best way to do the job. 



Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltageâ€”1000V to 1500V typicallyâ€”is induced in the coil. This current goes the same direction the original current didâ€”so it slows the contact openingâ€”allowing arcing, chatter, bouncing, contact welding and even re-closure!  Perihelion Design sells 18V 600W Bi-Directional Zener Transient Voltage Suppressors P6KE18CA (for 14.5V systems) that provide the most modern technical solution to relay coil suppression. 



See my website or buy your own. The Gigavac GX11 contactor already has bidirectional zeners for coil suppression. Gee, I wonder why!?



This issue has been argued here for years, so ignore me Bob.



"When I look up at the night sky and think about the billions of stars out there, I think to myself: I'm amazing."

              - Peter Serafinowicz

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Jul 08, 2009 7:09 am Post subject: Spike catcher diode

At 10:53 AM 7/7/2009, you wrote:

  	  Quote: 	
		   On the stock Van’s battery contactor, there is only three terminals (two 5 1/6 and one 3/16 front and center).  I am unsure where to install the IN5400 diode.  Can anyone comment on proper placement?  Also, what about the diode placement on the Van’s stock starter contactor?  Please excuse my very “green” hands regarding electronics…learning!

 	


    One of the battery contactor's large terminals

    should be marked "BAT". The diode's banded end

    connects to this terminal. The other end goes

    to the 3/16" terminal.



    This was the image of Van's starter contactor

    from his website.   



 [img]cid:.0[/img]



 

    The right small terminal is marked "I" and

    is not used. The left small terminal is power

    from the starter push button on the panel.

    The banded end of the diode connects to

    this terminal also. The other end connects to

    one of the contactor's mouning bolts

    which is also airframe ground.



 



 

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

1ac610.jpg

Description:

Filesize:

24.5 KB

Viewed:

13007 Time(s)

longg(at)pjm.com
Guest

Posted: Wed Jul 08, 2009 8:18 am Post subject: Spike catcher diode

Wade,  

   

Which approach (Zeners, Diodes or nothing) you choose is up to you. On my website link below you can see where I employed Van’s “blue” starter diode (I have an extra contactor ‘cause it’s IR) which uses the same approach. As Bob indicated I snaked the other end around the contactor to the mounting bolt. Van’s little direction sheet is quite clear – don’t deviate from it. In my case the solenoids are mounted on carbon fiber so I use a ground back to the FG. I haven’t decided if I’m going to use zeeners, diodes or just replace the solenoid on some scheduled basis. I’ve yet to see anything from anyone which shows how much longer (days, weeks or years) a solenoid lasts by adding these gadgets. The problem is real, but actual life expectancy needs to be measured to satisfy my interest. If you are the typical pilot which flies 35 hours / year it will fail from sitting around before it fails from arching.  

   

http://2.bp.blogspot.com/_hkAHk0Xu6wo/SdymLdP-KbI/AAAAAAAAA1A/rF4p8Xvi2UU/s1600-h/IMG_1312.JPG  

   

Glenn  

       

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Wade Roe

 Sent: Tuesday, July 07, 2009 11:54 AM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: Spike catcher diode   

  

  

   

On the stock Van’s battery contactor, there is only three terminals (two 5 1/6 and one 3/16 front and center).  I am unsure where to install the IN5400 diode.  Can anyone comment on proper placement?  Also, what about the diode placement on the Van’s stock starter contactor?  Please excuse my very “green” hands regarding electronics…learning!  

   

Thanks!   

     

Wade Roe  

   

EAA 557  

Aeronca 7AC flying  

RV-7 nearing completion  

   

  

--

mprather(at)spro.net
Guest

Posted: Wed Jul 08, 2009 8:59 am Post subject: Spike catcher diode

My thinking is that going without spike protection will cause the

controlling switch to have a shorter service life.  The high voltage is

across the coil...  ANY of the spike protection methods will provide the

controlling switch with a relatively easy life.



The question of WHICH protection method is about RELAY performance and

life.  Then too I would expect many of the relays in the airplane to not

particularly care about which protection method is employed.  Many of them

aren't switching very high current, at least not very often.  The

alternator relay should last "forever"  as it should rarely if ever be

asked to switch the alternator when it's making much current.



The starter relay is the one that regularly gets hit hard - switching

hundreds of amps in many aircraft each flight.  Setting that relay up to

open and close as succinctly as possible should help its service life.  I

would think electrically operated landing gear controlling relays would be

the next one in terms of severity of duty.

Regards,



Matt-

[quote] Wade,



 Which approach (Zeners, Diodes or nothing) you choose is up to you. On

 my website link below you can see where I employed Van's "blue" starter

 diode (I have an extra contactor 'cause it's IR) which uses the same

 approach. As Bob indicated I snaked the other end around the contactor

 to the mounting bolt. Van's little direction sheet is quite clear -

 don't deviate from it. In my case the solenoids are mounted on carbon

 fiber so I use a ground back to the FG. I haven't decided if I'm going

 to use zeeners, diodes or just replace the solenoid on some scheduled

 basis. I've yet to see anything from anyone which shows how much longer

 (days, weeks or years) a solenoid lasts by adding these gadgets. The

 problem is real, but actual life expectancy needs to be measured to

 satisfy my interest. If you are the typical pilot which flies 35 hours /

 year it will fail from sitting around before it fails from arching.



 http://2.bp.blogspot.com/_hkAHk0Xu6wo/SdymLdP-KbI/AAAAAAAAA1A/rF4p8Xvi2U

 U/s1600-h/IMG_1312.JPG



 Glenn



 From: owner-aeroelectric-list-server(at)matronics.com

 [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Wade

 Roe

 Sent: Tuesday, July 07, 2009 11:54 AM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: Spike catcher diode



 On the stock Van's battery contactor, there is only three terminals (two

 5 1/6 and one 3/16 front and center).  I am unsure where to install the

 IN5400 diode.  Can anyone comment on proper placement?  Also, what about

 the diode placement on the Van's stock starter contactor?  Please excuse

 my very "green" hands regarding electronics...learning!



 Thanks!



 Wade Roe



 EAA 557



 Aeronca 7AC flying



 RV-7 nearing completion



 --

wroe1(at)dbtech.net
Guest

Posted: Wed Jul 08, 2009 2:13 pm Post subject: Spike catcher diode

Thanks for everyone’s comments.  

     

Wade Roe  

   

  

-----Original Message----  



 From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III

 Sent: Wednesday, July 08, 2009 10:07 AM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: AeroElectric-List: Spike catcher diode   

   

At 10:53 AM 7/7/2009, you wrote: <![if !supportLineBreakNewLine]> <![endif]>  

On the stock Van’s battery contactor, there is only three terminals (two 5 1/6 and one 3/16 front and center).  I am unsure where to install the IN5400 diode.  Can anyone comment on proper placement?  Also, what about the diode placement on the Van’s stock starter contactor?  Please excuse my very “green” hands regarding electronics…learning!  



    One of the battery contactor's large terminals

    should be marked "BAT". The diode's banded end

    connects to this terminal. The other end goes

    to the 3/16" terminal.

 

    This was the image of Van's starter contactor

    from his website.   

 

 [img]cid:image001.jpg(at)01C9FFED.7DF8A8F0[/img]

 

 

    The right small terminal is marked "I" and

    is not used. The left small terminal is power

    from the starter push button on the panel.

    The banded end of the diode connects to

    this terminal also. The other end connects to

    one of the contactor's mouning bolts

    which is also airframe ground.

 

 

  <![if !supportLineBreakNewLine]> <![endif]>    

       Bob . . .

 

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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

image001.jpg

Description:

Filesize:

24.5 KB

Viewed:

12999 Time(s)

bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Fri Jul 10, 2009 2:35 am Post subject: Spike catcher diode

7/10/2009



Hello Glenn, You wrote: "I haven't decided if I'm going to use zeeners, 

diodes or just replace the solenoid on some scheduled basis. I've yet to see 

anything from anyone which shows how much longer (days, weeks or years) a 

solenoid lasts by adding these gadgets. The problem is real, but actual life 

expectancy needs to be measured to satisfy my interest."



I think that the primary purpose of a spike catcher device is to protect the 

points in the switch controlling the current through the solonoid coil. The 

switch points are much more fragile and susceptible to failure than the 

solonoid contact points.



We frequently see reports of switch point failures, particularly in the 

keyed ignition switches.



'OC' Says: "The best investment we can make is the effort to gather and 

understand knowledge."



===========================================



Time: 09:18:10 AM PST US

Subject: RE: Spike catcher diode

From: <longg(at)pjm.com>



Wade,

Which approach (Zeners, Diodes or nothing) you choose is up to you. On

my website link below you can see where I employed Van's "blue" starter

diode (I have an extra contactor 'cause it's IR) which uses the same

approach. As Bob indicated I snaked the other end around the contactor

to the mounting bolt. Van's little direction sheet is quite clear -

don't deviate from it. In my case the solenoids are mounted on carbon

fiber so I use a ground back to the FG. I haven't decided if I'm going

to use zeeners, diodes or just replace the solenoid on some scheduled

basis. I've yet to see anything from anyone which shows how much longer

(days, weeks or years) a solenoid lasts by adding these gadgets. The

problem is real, but actual life expectancy needs to be measured to

satisfy my interest. If you are the typical pilot which flies 35 hours /

year it will fail from sitting around before it fails from arching.

http://2.bp.blogspot.com/_hkAHk0Xu6wo/SdymLdP-KbI/AAAAAAAAA1A/rF4p8Xvi2U

U/s1600-h/IMG_1312.JPG

Glenn

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jul 10, 2009 10:50 am Post subject: Spike catcher diode

At 09:13 AM 7/8/2009, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Eric M. Jones" <emjones(at)charter.net>



 This issue has been argued here for years, so spare me your flames Bob. 	


    Please cite any posting I've made that could be

    reasonably (or even unreasonably) described as a

    "flame". They're all in the archives . . . cut and

    paste a direct quotation please.



 

  	  Quote: 	
		  Today, no electronic engineer recommends diodes for contactor coil suppression. They are not the best, nor the second, nor the third, nor even fourth best way to do the job. 	


    "The job" is not a constant . . . The means

    by which "the job" is accomplished is also not

    a constant. Many papers have been written on

    replay performance and system integration issues.

    Some were done by very competent designers who

    were marginal writers/teachers. For example: In

    the paper at:



  http://www.aeroelectric.com/Reference_Docs/Tyco/Tyco-Paper_on_Coil_Suppression.pdf 



    The paper opens with a concern for damage to

    normally open contacts that are switching high-

    inrush currents and attributes this to selection

    of coil suppression technique. In fact, the damage

    being cited is mostly a matter of contact bounce

    during a stressful portion of the operating cycle

    where contacts close, open and re-close

    perhaps a dozen times (at the worst possible moment)

    when the switched currents are many times higher than the

    steady state ratings of the contacts.



    Further, coil suppression has nothing to do with

    contactor performance on energizing the coil, only

    upon the de-energizing event.



    Keep in mind too that these guys write about

    RELAYS rated to advertised service life in tens of

    thousands if not hundreds of thousands of cycles.

    We're discussing battery and starter contactors

    that will probably fail due to corrosion before they

    die from service life stresses.



    Finally, I did real studies of changes to contact

    spreading velocity at de-energization for the

    two most aggressive devices in the airplane . . .

    battery and starter contactors. I thought I might

    have obvserved a 2 or 3% increase in arcing time

    for diode versus NO coil suppression. How does this

    drive a decision to put the hex on the lowly diode

    coil suppressor?



  	  Quote: 	
		  Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltageâ€”1000V to 1500V typicallyâ€”is induced in the coil. This current goes the same direction the original current didâ€”so it slows the contact openingâ€”allowing arcing, chatter, bouncing, contact welding and even re-closure!  Perihelion Design sells 18V 600W Bi-Directional Zener Transient Voltage Suppressors P6KE18CA (for 14.5V systems) that provide the most modern technical solution to relay coil suppression. 



 See my website or buy your own. The Gigavac GX11 contactor already has bidirectional zeners for coil suppression. Gee, I wonder why!?\ 	


    I can suggest a good reason why: Simple diodes are

    polarity sensitive . . . I.e. if you build the diode

    into the contactor, options for coil connection are

    bounded by polarity of the diode. In starter

    contactors where diodes are commonly built in, the

    base of the contactor is always (-) so the built in

    diode offers low risk for miswiring. Bi-directional

    Transorbs are goof-proof.



    The bi-directional zener offers a form of coil energy

    suppression that is not polarity sensitive and dissipates

    stored inductive energy in a combination of coil resistance

    and I*E product of the zener. Further current tending

    to keep the contactor closed after deenergizing has 

    a lower on-set value . . . hence the faster drop-out

    response.



  	  Quote: 	
		  This issue has been argued here for years, so ignore me Bob. 	


    So why bring it up again? I've measured, demonstrated and

    explained the value/function of the various coil transient

    suppression methods on the devices we're talking about . . .

    CONTACTORS.



  http://tinyurl.com/mcgg87 



    On your website at:



  http://www.periheliondesign.com/suppressors.htm



    you say . . .



    "Thus a large voltage1000V to 1500V typicallyis induced

     in the coil. This current goes the same direction the original

     current didso it slows the contact openingallowing arcing,

     chatter, bouncing, contact welding and even re-closure!"



    The first statement is correct, the voltage is high . . . but

    fails to say where it goes or what devices are placed at risk.

    A diode delays contact opening after the coil power is removed. But

    differences in contact spreading velocity are so small (if they

    exist at all) as to be difficult to measure. I challenge you to

    go to the workbench and show me a setup that produces bounce,

    chatter, increased arcing, tendencies to weld N.O. contacts

    upon de-energization, and/or evidence of re-closure as a

    consequence of simple diode coil suppression.



    If not demonstrable, how about a hypothesis as to how

    contacts that are moving away from each other are subject

    to a force that accelerates the contact mass in the opposite

    direction and effects re-closure? May I suggest this notion is

    absurd the the extreme?



    Your hypothesized 60v transient generated by simply turning

    off a large load is also in error. This event happens during

    the automotive definition of load dump that includes a

    BATTERY DISCONNECT. Alternators that go through MPA's

    rebuild facilities are tested for it's effect on the

    alternator . . . believe me it can be a whole lot worse

    than 60V. But this is rare in airplanes. What's the likelihood

    that dropping a max rated load is exactly coincident with

    opening the battery contactor? In your functional description

    at:



  http://www.periheliondesign.com/suppressors/Whackjack%20Manual.pdf

 

    There's no mention of battery disconnect . . . hence the

    60v number is hyperbolic persuasion. Your citation of

    FAR 25.581 is equally hyperbolic. If you're going to evoke

    lightning qualification issues to an RV, then believe me,

    the task is about 100x more complex than adding a "WhackJack"

    to the system.



    I've managed numerous investigations into relay and switch

    contact failures in 40+ years of hammering on airplanes.

    It was not uncommon to discover things about some products

    than the "engineers" and "manufacturer's reps" assigned to

    support those products did not know. Quite often,

    those individuals were tasked with supporting a legacy

    product they didn't design and never integrated into

    a system.



    There's an archive of Tyco publications on the subject

    at:



  http://www.aeroelectric.com/Reference_Docs/Tyco/



    These are largely factual and the ideas presented are useful

    to consider where applicable . . . but they don't apply

    to what we've been talking about.



    If you choose to play in this sandbox, bring the right

    shovel, bucket and support them with a willingness to explain

    and teach. I'm sure that your products perform as they

    are intended to by their designers. But their prophylactic

    application to ward off the gremlins described on your

    website is not consistent with what we have known about electrical

    systems (and their component parts) in airplane for over 100 years.



    Bob . . .



 

     [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jul 10, 2009 11:35 am Post subject: Spike catcher diode

 	  Quote: 	
		  I haven't decided if I'm going to use zeeners, diodes or just 

replace the solenoid on some scheduled basis. I've yet to see 

anything from anyone which shows how much longer (days, weeks or 

years) a solenoid lasts by adding these gadgets.


	


    The inclusion of coil suppression is for the benefit of the

    controlling device (switch or push-button).  From the time

    that batteries and starters went into light airplanes (1945?)

    until the rectifier diodes came to Cessna's attention (1963?)

    there was no coil suppression on battery or starter contactors.



    We had a devil of a time converting a leaded electronic component

    into an airplane part. We COULD have attached the diodes like

    this . . .



http://www.aeroelectric.com/Pictures/Contactors/s701-1.jpg



    But somebody decided to mount the diodes on little strips

    of phenolic sheet with eyelets at the ends to accept

    screws and wires with terminals crimped on them. Added a

    whole lot of labor and fragility to an otherwise inexpensive,

    robust device. I note that the Cessna Service parts lists

    still show a lot of "diode assemblies" for $15 to $50. So

    I guess they're still sticking diodes on some form of

    built-up assembly.



    Even today, plain-vanilla diodes are used across contactors

    in production aircraft.



 	  Quote: 	
		    The problem is real, but actual life expectancy needs to be 

 measured to satisfy my interest.


	


    Excellent question. I don't recall that we were ever aware

    of a service life "problem" with either contactors or their

    controlling switches in the years before diodes. But I

    recall Gordon Wood (our PhD physicist) putting a H-P peak-

    reading voltmeter across a contactor coil, seeing a 500+ volt

    reading and saying, "Hot damn . . . we need to do something

    about that!"  And we did.



    Given that we were unaware of service life issues attributable

    to LACK of DIODES, we were destined to be equally ignorant of

    service life benefits after diodes were ADDED. But we sure took

    care of that 500v spike! I don't think Gordo ever put a 'scope

    on the system to see where the spike goes. I suspect he would

    have seen this:



http://www.aeroelectric.com/articles/Spike_Catching/CH_Opening_No_Suppression.gif



    Noise conducted to the bus is very low energy, low amplitude

    compared to what the controlling switch sees.

  If you are the typical pilot which flies 35 hours / year it will 

fail from sitting around before it fails from arching.



    Exactly! There's a ton of papers written to the task of

    wringing the last few hours of service life from various products

    rated in gazillions of cycles.



    But if there was ever a low duty-cycle application for any

    electro-whizzy, it's the personally owned light airplane,

    snow-mobile, or bass boat.



    Your perception of effects of age and environment being

    more profound than effects of service life is quite

    accurate!



    Bob . . .

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Mon Jul 13, 2009 10:45 am Post subject: Spike Catcher Diode

As long as this subject has bubbled up, I'd like to  know how to test my contactors to see if they have internal SCD's. It's been  nagging at me for  awhile and I'm nearing installing them.

  

 Thanks,

 John

  

   [quote][b]

wroe1(at)dbtech.net
Guest

Posted: Mon Jul 13, 2009 1:52 pm Post subject: Spike Catcher Diode

I know that the Vans contactors do not have diodes.  Not sure about those from other sources.  



Wade RoeIPhone message





On Jul 13, 2009, at 1:37 PM, "John Burnaby" <jonlaury(at)impulse.net (jonlaury(at)impulse.net)> wrote:



[quote]  As long as this subject has bubbled up, I'd like to  know how to test my contactors to see if they have internal SCD's. It's been  nagging at me for  awhile and I'm nearing installing them.

  

 Thanks,

 John

  

    	  Quote: 	
		  



	


[b]

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 13, 2009 4:35 pm Post subject: Spike Catcher Diode

At 01:37 PM 7/13/2009, you wrote:

  	  Quote: 	
		   As long as this subject has bubbled up, I'd like to know how to test my contactors to see if they have internal SCD's. It's been nagging at me for  awhile and I'm nearing installing them.

 	


    The only contactors that I've sold with built in

    diodes said so on the bottom of the mounting

    bracket. If you have a 'scope it's easy to tell

    in a simple bench test setup (or just keep your

    fingers across the coil contacts while you break

    the circuit . . . if you don't "jump" then

    there's a diode installed.



    Given that they are easy to get and inexpensive,

    put them on unless you already KNOW that they're

    present inside. Very few contactors come with them

    built in . . . I had to search for the one I

    sold.



 

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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



     [quote][b]

mprather(at)spro.net
Guest

Posted: Mon Jul 13, 2009 5:10 pm Post subject: Spike Catcher Diode

Seems like you could test for a diode with a 9V battery and a volt meter..

 Apply voltage to the coil in one direction, and something close to the

full voltage of the battery should be present..  Swap the terminals on the

battery, and the voltage on the coil should be limited to a diode drop -

maybe about 0.8V depending on what kind of diode they use.



I don't think this method would put any of the components involved at risk.

Matt-



 	  Quote: 	
		   At 01:37 PM 7/13/2009, you wrote:

>As long as this subject has bubbled up, I'd like to know how to test

>my contactors to see if they have internal SCD's. It's been nagging

>at me for  awhile and I'm nearing installing them.



     The only contactors that I've sold with built in

     diodes said so on the bottom of the mounting

     bracket. If you have a 'scope it's easy to tell

     in a simple bench test setup (or just keep your

     fingers across the coil contacts while you break

     the circuit . . . if you don't "jump" then

     there's a diode installed.



     Given that they are easy to get and inexpensive,

     put them on unless you already KNOW that they're

     present inside. Very few contactors come with them

     built in . . . I had to search for the one I

     sold.

         Bob . . .



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

         ( . . .  a long habit of not thinking   )

         ( a thing wrong, gives it a superficial )

         ( appearance of being right . . .       )

         (                                       )

         (                  -Thomas Paine 1776-  )

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

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jul 14, 2009 4:33 am Post subject: Spike Catcher Diode

At 08:03 PM 7/13/2009, you wrote:

 	  Quote: 	
		  



Seems like you could test for a diode with a 9V battery and a volt meter..

  Apply voltage to the coil in one direction, and something close to the

full voltage of the battery should be present..  Swap the terminals on the

battery, and the voltage on the coil should be limited to a diode drop -

maybe about 0.8V depending on what kind of diode they use.


	


    MUCH better idea! Actually, if the 9V battery is fresh,

    the contactor will pull in for BOTH directions of battery

    connection if NO diode is present . . . and FAIL to pull

    in for ONE direction if diode IS present.

        Bob . . .



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

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum