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Lancair Flap Drive Relay Wiring Question

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Valin

Joined: 13 Apr 2010
Posts: 31
Location: Colorado

Posted: Sun May 23, 2010 8:23 am Post subject: Lancair Flap Drive Relay Wiring Question

Hey Aeroelectric Gang,  

   

I’m still working on wiring diagrams for our Lancair Legacy under construction.  I have a question on the flap drive wiring I’d appreciate feedback on...    

   

Rather than using a DPDT switch wired up to change polarity for the linear electro-mechanical actuator (EMA) to drive the flaps up and down, Lancair recommends two DPST relays with proper (see below) wiring to change polarity and provide immediate braking of the actuator.  Without this circuitry the EMA will coast after releasing the switch which is a serious problem when the flaps are at their limits.    

   

A couple of years ago, when we assembled and installed our flaps, I quickly wired this up and confirmed that without the relays it coasts quite a bit and with this relay circuit  the EMA/flaps stop immediately.  

   

So my question is, how does it accomplish this?  I’ve attached my draft wiring diagram where I’ve created what I think is the relay circuit but am not sure.  The wiring between everything is accurate.  All Lancair provides in their manual is a pictorial of the relay wiring and a schematic of the circuit (see second image below).  I’m having to guess that the terminals 7 and 8 in the relay circuit control the switch and that it’s normally closed to pole 2 (the relay schematic from the Lancair manual is the last image below).  

   

Does this braking effect happen because of the collapsing solenoid field provides a brief voltage spike of opposite polarity?    

   

Thanks,  

   

Valin  

Lancair Legacy Project  

Houston, TX USA  

   

   

Here’s  my rendering of the flap drive wiring as I understand it:  

   

[img]cid:image001.jpg(at)01CAFA69.F50E8500[/img]  

   

[img]cid:image002.jpg(at)01CAFA69.F50E8500[/img]  

   

[img]cid:image005.jpg(at)01CAFA69.F50E8500[/img]

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retasker(at)optonline.net
Guest

Posted: Sun May 23, 2010 10:13 am Post subject: Lancair Flap Drive Relay Wiring Question

When one selects neither up or down with the switch, the motor is 

shorted by the relays (each side of the motor goes through its 

respective relay's pins 5&6 through the NC connection to pins 1&2 which 

are both connected to ground). The fact that they are connected to 

ground is incidental. When the power leads of a running DC motor are 

shorted together, the motor acts as a generator running into a short. 

This almost instantaneously absorbs the rotational energy of the motor, 

stopping it very quickly as you saw. If the leads were just disconnected 

from power the only way for the rotational energy to dissipate is 

through frictional losses in the motor and the flap mechanism - which 

allows the whole system to coast to a stop as you found.



Dick Tasker



Valin & Allyson Thorn wrote:

 	  Quote: 	
		  

 Hey Aeroelectric Gang,



 I’m still working on wiring diagrams for our Lancair Legacy under 

 construction. I have a question on the flap drive wiring I’d 

 appreciate feedback on...



 Rather than using a DPDT switch wired up to change polarity for the 

 linear electro-mechanical actuator (EMA) to drive the flaps up and 

 down, Lancair recommends two DPST relays with proper (see below) 

 wiring to change polarity and provide immediate braking of the 

 actuator. Without this circuitry the EMA will coast after releasing 

 the switch which is a serious problem when the flaps are at their limits.



 A couple of years ago, when we assembled and installed our flaps, I 

 quickly wired this up and confirmed that without the relays it coasts 

 quite a bit and with this relay circuit the EMA/flaps stop immediately.



 So my question is, how does it accomplish this? I’ve attached my draft 

 wiring diagram where I’ve created what I think is the relay circuit 

 but am not sure. The wiring between everything is accurate. All 

 Lancair provides in their manual is a pictorial of the relay wiring 

 and a schematic of the circuit (see second image below). I’m having to 

 guess that the terminals 7 and 8 in the relay circuit control the 

 switch and that it’s normally closed to pole 2 (the relay schematic 

 from the Lancair manual is the last image below).



 Does this braking effect happen because of the collapsing solenoid 

 field provides a brief voltage spike of opposite polarity?



 Thanks,



 Valin



 Lancair Legacy Project



 Houston, TX USA



 /Here’s my rendering of the flap drive wiring as I understand it:/



 Lancair Flap Drive Wiring Drawing.jpg



 Legacy Flap Wiring Pictorial.jpg



 Flap Relay Schematic.jpg




	


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Valin

Joined: 13 Apr 2010
Posts: 31
Location: Colorado

Posted: Sun May 23, 2010 10:13 am Post subject: Lancair Flap Drive Relay Wiring Question

Ironically, I was looking at the Aeroelectric discussions from the last week and saw that Bob in another discussion last Wednesday related to flap drives already explained the motor braking is achieved by grounding (shorting) both sides of the motor rather than just opening the circuit…  

   

     “Note that in the OFF position, both relays  

     are relaxed and the wiring places a dead short  

     across the motor. This is ESPECIALLY useful in  

     PM motors to supply electro-dynamic braking  

     to the motor. Coasting is reduced to a small  

     fraction of what you get when you simply open  

     the motor's power circuit to shut it off.  

   

     Bob . . .”  

   

Thanks Bob.  Sorry I didn’t search the archives more thoroughly before posting my question.  I’d still be interested to know if it looks like I’ve drawn the wiring diagram and relay circuit correctly.  

   

Valin  

   

   

       

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Valin & Allyson Thorn

 Sent: Sunday, May 23, 2010 11:21 AM

 To: aeroelectric-list(at)matronics.com

 Subject: Lancair Flap Drive Relay Wiring Question  

  

  

   

Hey Aeroelectric Gang,  

   

I’m still working on wiring diagrams for our Lancair Legacy under construction.  I have a question on the flap drive wiring I’d appreciate feedback on...    

   

Rather than using a DPDT switch wired up to change polarity for the linear electro-mechanical actuator (EMA) to drive the flaps up and down, Lancair recommends two DPST relays with proper (see below) wiring to change polarity and provide immediate braking of the actuator.  Without this circuitry the EMA will coast after releasing the switch which is a serious problem when the flaps are at their limits.    

   

A couple of years ago, when we assembled and installed our flaps, I quickly wired this up and confirmed that without the relays it coasts quite a bit and with this relay circuit  the EMA/flaps stop immediately.  

   

So my question is, how does it accomplish this?  I’ve attached my draft wiring diagram where I’ve created what I think is the relay circuit but am not sure.  The wiring between everything is accurate.  All Lancair provides in their manual is a pictorial of the relay wiring and a schematic of the circuit (see second image below).  I’m having to guess that the terminals 7 and 8 in the relay circuit control the switch and that it’s normally closed to pole 2 (the relay schematic from the Lancair manual is the last image below).  

   

Does this braking effect happen because of the collapsing solenoid field provides a brief voltage spike of opposite polarity?    

   

Thanks,  

   

Valin  

Lancair Legacy Project  

Houston, TX USA  

   

   

Here’s  my rendering of the flap drive wiring as I understand it:  

   

   

   

   

   

   

        [quote][b]

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Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sun May 23, 2010 12:21 pm Post subject: Lancair Flap Drive Relay Wiring Question

Valin;  

   

The wiring as you’ve drawn it appears correct and will function as desired. The second pole of the manual switch which is connected to your power source is not strictly required. Terminals 3 & 4 of the relays could  go directly to your circuit protection bypassing the left pole of your switch. A SPDT momentary switch wired as the right side of your DPDT controlling the relays will give the exact same functionality. HOWEVER that second pole gives double redundancy for turning off power to the motor when you release the switch and is probably a good idea.   

   

Also if I understand your explanation of how the flaps work on this aircraft it would appear that the notes on the wires leading to the actuator are incorrect. The drawing shows the red motor lead connected to positive battery power and the black lead grounded. Your explanation says this is extending the flaps and the down limit will stop this motion. The notes associated with the wires are contradictory. (Red lead negative (Therefore Black lead positive) to extend but it also says black lead positive (therefore red lead negative) to retract. Obvious contradiction somewhere). The drawing as shown supports your explanation and it is the notes which appear confused.   

   

Bob McC  

   

   

           

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Valin & Allyson Thorn

 Sent: Sunday, May 23, 2010 2:13 PM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: Lancair Flap Drive Relay Wiring Question  

  

   

Ironically, I was looking at the Aeroelectric discussions from the last week and saw that Bob in another discussion last Wednesday related to flap drives already explained the motor braking is achieved by grounding (shorting) both sides of the motor rather than just opening the circuit…  

   

     “Note that in the OFF position, both relays  

     are relaxed and the wiring places a dead short  

     across the motor. This is ESPECIALLY useful in  

     PM motors to supply electro-dynamic braking  

     to the motor. Coasting is reduced to a small  

     fraction of what you get when you simply open  

     the motor's power circuit to shut it off.  

   

     Bob . . .”  

   

Thanks Bob.  Sorry I didn’t search the archives more thoroughly before posting my question.  I’d still be interested to know if it looks like I’ve drawn the wiring diagram and relay circuit correctly.  

   

Valin  

   

   

       

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Valin & Allyson Thorn

 Sent: Sunday, May 23, 2010 11:21 AM

 To: aeroelectric-list(at)matronics.com

 Subject: Lancair Flap Drive Relay Wiring Question  

  

  

   

Hey Aeroelectric Gang,  

   

I’m still working on wiring diagrams for our Lancair Legacy under construction.  I have a question on the flap drive wiring I’d appreciate feedback on...    

   

Rather than using a DPDT switch wired up to change polarity for the linear electro-mechanical actuator (EMA) to drive the flaps up and down, Lancair recommends two DPST relays with proper (see below) wiring to change polarity and provide immediate braking of the actuator.  Without this circuitry the EMA will coast after releasing the switch which is a serious problem when the flaps are at their limits.    

   

A couple of years ago, when we assembled and installed our flaps, I quickly wired this up and confirmed that without the relays it coasts quite a bit and with this relay circuit  the EMA/flaps stop immediately.  

   

So my question is, how does it accomplish this?  I’ve attached my draft wiring diagram where I’ve created what I think is the relay circuit but am not sure.  The wiring between everything is accurate.  All Lancair provides in their manual is a pictorial of the relay wiring and a schematic of the circuit (see second image below).  I’m having to guess that the terminals 7 and 8 in the relay circuit control the switch and that it’s normally closed to pole 2 (the relay schematic from the Lancair manual is the last image below).  

   

Does this braking effect happen because of the collapsing solenoid field provides a brief voltage spike of opposite polarity?    

   

Thanks,  

   

Valin  

Lancair Legacy Project  

Houston, TX USA  

   

   

Here’s  my rendering of the flap drive wiring as I understand it:  

   

   

   

   

   

    	  Quote: 	
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       [quote][b]

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_________________
Bob McC
Falco #908
(just starting)

jschroeder(at)perigee.net
Guest

Posted: Sun May 23, 2010 12:29 pm Post subject: Lancair Flap Drive Relay Wiring Question

Valin-



I would recommend using the circuitry that Lancair has in its manual. It

incorporates what Bob has mentioned (dual relays) in his response to you,

and it works very well - stops instantly when the switch springs back to

the central/neutral position.



I am on the road, but when I get home tomorrow, I can send you the page

from my wirebook with the wiring diagram and pinout of the relays. Let me

know if you want it. I could not download your diagram to enable me to

compare it to mine.  Send it off line if you want me to look it over. IMHO,

this is not a circuit in your system that needs any modification.



Regards,



John Schroeder

Lancair ES - 338 hours





 	  Quote: 	
		  



Ironically, I was looking at the Aeroelectric discussions from the last

week
	


 	  Quote: 	
		  and saw that Bob in another discussion last Wednesday related to flap

drives
	


 	  Quote: 	
		  already explained the motor braking is achieved by grounding (shorting)

both
	


 	  Quote: 	
		  sides of the motor rather than just opening the circuit.



 



     "Note that in the OFF position, both relays



     are relaxed and the wiring places a dead short



     across the motor. This is ESPECIALLY useful in



     PM motors to supply electro-dynamic braking



     to the motor. Coasting is reduced to a small



     fraction of what you get when you simply open



     the motor's power circuit to shut it off.



 



     Bob . . ."

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longg(at)pjm.com
Guest

Posted: Mon May 24, 2010 6:14 am Post subject: Lancair Flap Drive Relay Wiring Question

Do Not Archive



Valin,



I agree with John. Unless you are just curious, don't change a good,

simple thing. I'm sure you've got more important challenges to attend

to.



Glenn Long - Legacy FG.



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Valin

Joined: 13 Apr 2010
Posts: 31
Location: Colorado

Posted: Mon May 24, 2010 7:34 am Post subject: Lancair Flap Drive Relay Wiring Question

Thanks Glenn and John. I wasn't proposing to change it. I wanted to  

understand how the set up made the flap motor stop without coasting  

and confirm that I'd reconstructed the relay's internal circuit  

acurately.  I understand it well now and think I captured the relay  

internal circuit correctly.



Thanks again,



Valin



Sent from my iPhone -- so spleling errors likely...



On May 24, 2010, at 9:12 AM, <longg(at)pjm.com> wrote:



[quote] 



 Do Not Archive



 Valin,



 I agree with John. Unless you are just curious, don't change a good,

 simple thing. I'm sure you've got more important challenges to attend

 to.



 Glenn Long - Legacy FG.



 --

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