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Z19 first try and smoke/wire melted I did a mistake

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jun 17, 2018 7:30 am Post subject: Z19 first try and smoke/wire melted I did a mistake

At 08:56 PM 6/16/2018, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Achille" <mickael.t(at)live.fr>



 Thank you bob for you reply. I hope to find just the diode end the wire U/S. Many thanks.



 I have to check just the integrity of contactor ground wire (master switch to the ground bus) easily accessible or I could have other wire damaged ? 	


   If the burned wire is in a bundle, there is a

   probability for damage to adjacent wires that

   should be investigated.



  	  Quote: 	
		  Because all my wires are set in harness with sleeve. 	


    . . . oh . . . fooey. Not an enviable task.

    You might open just a portion of the sleeved

    bundle for inspection. Find the contactor control

    wire as assess damage to it's insulation and

    propagation of damage to other wires.



 

  	  Quote: 	
		  About the possible damage, with luck just this wire and diode. But without 

 Alternator diode couldn't be damage at least ? 	


    No, it's unlikely that the rest of the

    system suffered any damage. To connect the

    battery to the system, you have to close the

    battery contactor. When battery power is

    backwards, the diode across the contactor

    coil is essentially a dead short across the

    coil. If the diode is small (like a plastic

    1N4000 series) it may simply explode and

    remove itself from the equation. Not good.

    Then the contactor coil closes and reversed

    power is applied to the. This still isn't

    an automatic condition for total distaster.

    The alternator  diode array will now become

    reverse biased. The array is 6 to 9 diodes

    in series pairs that will (1) prevent the

    bus voltage from rising to more than a couple

    volts . . . for a short period of time. The

    b-lead protection device will operate and

    disconnect the alternator from the bus.



    After this time, all bets are off. But bus

    voltage does waayyyy negative to what ever

    the battery supplies.



    If your contactor diode is mechanically

    intact AND the control wire is burned, this

    tells us that the contactor never closed.

    You'll also find that your b-lead protection

    is closed.



  	  Quote: 	
		  and my ignitions and transpondeur ? (I checked on the user manuel they told that inversion of polarity damage it) But in the case of switch was in OFF on the transpondeur (for exemple) it can damage it ? (I ask the question because I was doing a quote of my error to be prepared in the event of I have to change part.. and total price become quickly crazy) 	


    I think your misery for having suffered this

    event will be limited to inspection and repair

    of the burned wire and replacement of the

    contactor coil suppression diode.



 

 

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jun 18, 2018 5:40 am Post subject: Z19 first try and smoke/wire melted I did a mistake

At 03:52 PM 6/17/2018, you wrote:

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



 It does not matter what kind of arc suppression device is in parallel with the contactor coil.  That coil is going to energize when the switch is turned on (unless the master switch wire burns open).  A diode in series with the contactor coil would prevent it from being energized by a reverse polarity battery.  If a builder were concerned about reverse polarity, two diodes could be used, one in parallel with the coil and one in series.  But what about protection against line boys with 24 volt jumper cables? 	




 Yeah, I had a line-crew feller hook 28v to my 14v

 172XP for a start assist on a -5C morning in KC.

 He had his back turned to me and the WWII surplus,

 gas driven generator was pretty noisy so yelling

 was futile.



 I hit the starter and got a really energetic engine

 start. Only then did he hit the disconnect switch

 never having looked at me.  I wanted to get out and

  . . . well . . . but that would have called for

 stopping the engine.  A quick check of the panel didn't

 show evidence of damage so I chalked it up to experience

 and future planning:



 Me: You know this is a 14v airplane, right?



 LB: Sure



 Me: you know that you're not to take your eyes off

     me, or take your fingers off the switch at any

     time external power is on the airplane?



 LB: Yeah, sure.



 Me: You know that power doesn't go ON until I give

     you a thumbs up?



 LB: I can do that.



 Me; You know that thumbs down means turn it OFF?



 Lb: Okay.



 Me: You're a bright fellow.



 Then I tip him $5 and invite him to have a beer

 on me.



 REAL airplanes have ground power jacks fitted with

 polarity protection, ov protection and CREW CONTROLLED

 ground power contactors.



  https://goo.gl/xzixnk



 https://goo.gl/CbPgUw 



 

 

   Bob . . .

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Achille

Joined: 12 Jun 2017
Posts: 25
Location: Europe

Posted: Mon Jun 18, 2018 9:38 am Post subject: Re: Z19 first try and smoke/wire melted I did a mistake

I will advise you this weekend I will asses. 



The contactor wire is the only one that is alone, so it will be easy to change it if it's the only one that could be damage. In my mind it don't keep clear my mistake that it do du to lack of knowledge. I will see. 



For the protection i checked user manuel the only one things that have a protection for reversal is my old becker AR3201 that I have to change it before august 2018 du to eupean rules.. 



I hope you have right bob and I have no doubt. Just i did the quote in case of... 



I was thinking about one things. My ignitions have the case grounded and have the ground wire, both are grounded on the ground buses. I don't have short cut the ignition module ?

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jun 18, 2018 12:54 pm Post subject: Z19 first try and smoke/wire melted I did a mistake

At 12:38 PM 6/18/2018, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "Achille" <mickael.t(at)live.fr>



 I will advise you this weekend I will asses. 



 The contactor wire is the only one that is alone, so it will be easy to change it if it's the only one that could be damage. In my mind it don't keep clear my mistake that it do du to lack of knowledge. I will see. 	


  The only OTHER wires at risk would be those

  tightly bundled with the damaged wire. Even

  so, the 'damage' may be limited to staining

  of the insulation. If there are no wires in close

  proximity to the damaged one, then you're

  home almost free.



 

 

   Bob . . .

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Achille

Joined: 12 Jun 2017
Posts: 25
Location: Europe

Posted: Sun Jun 24, 2018 12:57 am Post subject: Re: Z19 first try and smoke/wire melted I did a mistake

At the end it cost me just a few cents, one diode and 3cm of wire. I just didn't test my ignition but all the others things are working. 



Thanks you bob !!!

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