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Flap Switch Protection

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frazitl

Joined: 04 Feb 2008
Posts: 9

Posted: Mon Feb 11, 2008 9:57 am Post subject: Flap Switch Protection

I'm using Van's electric flap motor with a on-off-(mom)on dpdt switch.  I'm

looking for a protection config. for the switch similar to that used on the

battery/starter contactors. Found one diagram on the web using two (Zeiner?)

15V diodes opposing each other across the motor wires, but I don't know the

pedigree of the design.  Is there a better way to do this, and if not will a

zeiner diode setup do what I'm trying to do - protect the switch?



Thanks in advance,



Terry Frazier

7A Finishing & Panel

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_________________
Terry Frazier
RV7A
Finishing

rv-9a-online(at)telus.net
Guest

Posted: Mon Feb 11, 2008 1:01 pm Post subject: Flap Switch Protection

That's my design.  Probably better to use a bidirectional Transzorb, but the

Zener's are what I had on hand.  If I do it again, I'd use a single P6KE16CA

(available from DigiKey).  A larger voltage rating is ok as well, just don't

go lower (in a 12 volt system).



Having said that, I've never heard of anyone burning out a switch with a

Van's flap motor.  I think the total stored energy is low compared to a

contactor coil, for example.



Vern Little



--

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gregory.scott1(at)virgin.
Guest

Posted: Mon Feb 11, 2008 1:05 pm Post subject: Flap Switch Protection

Terry,

You do not need any switch protection for the Van's Flap motor. The master 

and starter solenoids are a different thing thing alltogether. The solenoids 

when energized produce a strong electromagenetic field that collapes when 

de-energized.  This collapsing field causes a reversed EMF that will arc 

across the opening contacts eroding them in the process.  A diode is 

connected across the coil terminals to provide a path for this EMF, 

therefore protecting the switch contacts.  You named the diodes as "Zeiner" 

incorrect, they are Zener diodes, their useful characteristic is their 

ability  be non conducting in one direction only up to a designed (different 

value Zeners) voltage at which point they conduct readily.  They are useful 

for Over Voltage protection circuits with the addition of a few more 

components.  They will monitor a voltage level which if goes over the design 

voltage the Zener will conduct and trip the circuit protection, a circuit 

breaker or fuse.

    Hope this has been helpful,

Greg Scott

RV 4     UK reg.  G - RVIV



RV9 under construction

---

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nuckolls.bob(at)cox.net
Guest

Posted: Mon Feb 11, 2008 4:24 pm Post subject: Flap Switch Protection

At 09:43 AM 2/11/2008 -0800, you wrote:



 	  Quote: 	
		  

<fraziernv(at)earthlink.net>

I'm using Van's electric flap motor with a on-off-(mom)on dpdt switch.  I'm

looking for a protection config. for the switch similar to that used on the

battery/starter contactors. Found one diagram on the web using two (Zeiner?)

15V diodes opposing each other across the motor wires, but I don't know the

pedigree of the design.  Is there a better way to do this, and if not will a

zeiner diode setup do what I'm trying to do - protect the switch?


	


  PM motors are not very "inductive" . . . the

  switch used to control this motor would not

  benefit from a protective device like a transorb

  or zener.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

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Bob Barrow

Joined: 11 Jan 2006
Posts: 29

Posted: Tue Feb 12, 2008 5:07 am Post subject: Flap Switch Protection

Bob, For my Vans RV7 flap actuation system I used your Drawing Flaps 4.2 which utilises two S704-1 Relays and two NO/NC limit switches. 

 Is this still your recommended system for a situation where one wants the motor to be positively turned off at the flaps full up and full down position.

 Incidentally, are the relays in Drawing Flaps 4.2 simply required as part of the circuit logic, or do they serve a dual function in protecting the toggle switch from damage.

 Funny thing is that now I can't even find Drawing Flaps 4.2 on your site. Is it still there.

 Regards Bob Barrow

 11 Feb 2008 18:20:52 -0600

 	  Quote: 	
		   To: aeroelectric-list(at)matronics.com

 From: nuckolls.bob(at)cox.net

 Subject: Re: AeroElectric-List: Flap Switch Protection

 --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net>

 At 09:43 AM 2/11/2008 -0800, you wrote:

 >--> AeroElectric-List message posted by: "Terry Frazier" 

 ><fraziernv(at)earthlink.net>

 >

 >

 >I'm using Van's electric flap motor with a on-off-(mom)on dpdt switch. I'm

 >looking for a protection config. for the switch similar to that used on the

 >battery/starter contactors. Found one diagram on the web using two (Zeiner?)

 >15V diodes opposing each other across the motor wires, but I don't know the

 >pedigree of the design. Is there a better way to do this, and if not will a

 >zeiner diode setup do what I'm trying to do - protect the switch?

 PM motors are not very "inductive" . . . the

 switch used to control this motor would not

 benefit from a protective device like a transorb

 or zener.

 Bob . . .

 ----------------------------------------)

 ( . . . a long habit of not thinking )

 ( a thing wrong, gives it a superficial )

 ( appearance of being right . . . )

 ( )

 ( -Thomas Paine 1776- )

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

&=====================

 	  Quote: 	

Listen now! New music from the Rogue Traders.  [quote][b]

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nuckolls.bob(at)cox.net
Guest

Posted: Tue Feb 12, 2008 6:32 am Post subject: Flap Switch Protection

At 11:59 PM 2/12/2008 +1100, you wrote:



 	  Quote: 	
		  Bob, For my Vans RV7 flap actuation system I used your Drawing Flaps 4.2 

which utilises two S704-1 Relays and two NO/NC limit switches.



Is this still your recommended system for a situation where one wants the 

motor to be positively turned off at the flaps full up and full down position.


	


   You may not need the limit switches. If the actuator

   is fitted with a free-wheel mechanism at the extremes

   of travel, then you simply rig the flap extension

   mechanism such that flaps are fully extended and

   fully stowed at the mechanical limits of the

   actuator.



 	  Quote: 	
		  

Incidentally, are the relays in Drawing Flaps 4.2 simply required as part 

of the circuit logic, or do they serve a dual function in protecting the 

toggle switch from damage.


	


   The limit switches are not generally rated for

   the kinds of stresses posed by the motor. Further,

   we'd like to put a dead short on the motor when

   OFF . . . this is dynamic braking that reduces

   coasting.



 	  Quote: 	
		  

Funny thing is that now I can't even find Drawing Flaps 4.2 on your site. 

Is it still there.


	




   See 4th page of



http://www.aeroelectric.com/PPS/Flight/Flaps/Flaps.pdf

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

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