# Help wiring switch to vfd.



## woodtickgreg (Jul 7, 2013)

Well I am finally working on getting the south bend wired up. I got a new fully enclosed vfd, teco fm50-101. I understand how to wire the 110v input and the 220 3 phase output to the motor. The part that I dond understand and that the manual is not clear on at all is how to wire the stock cuttler hammer switch up. The manual says to use a 2 conductor shielded wire, I purchased that. I see on the vfd where the switch is supposed to be connected, it has fwd, rev, and I don't know if you are supposed to use 12v power or not? I really do not understand how this switch is supposed to be wired. I took some pics of the vfd and the switch in hopes that maybe some one here smarter than me can help me with this.


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## DMS (Jul 7, 2013)

I found the manual (they make it kind of tricky.. not sure why).

http://www.tecowestinghouse.com/products/Drives/fm50.html

It's the lowest link in the right hand panel. Check out page 17 of the manual. Looks like the 12V is for digital (switch) control power, and the 10v is analog for the speed control (10k ohm potentiometer).


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## woodtickgreg (Jul 7, 2013)

DMS said:


> I found the manual (they make it kind of tricky.. not sure why).
> 
> http://www.tecowestinghouse.com/products/Drives/fm50.html
> 
> It's the lowest link in the right hand panel. Check out page 17 of the manual. Looks like the 12V is for digital (switch) control power, and the 10v is analog for the speed control (10k ohm potentiometer).



Yes I have that, but I still don't understand wher the 2 wires are supposed to connect to? I'm assuming one to fwd and one to rev, but how and where to connect on the switch. I'm guessing the top 2 terminals of the switch would be used?


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## Codered741 (Jul 7, 2013)

DMS is correct.  You should connect the 12v to FWD or REV to make the VFD run that direction. 

You simply need to find two sets of terminals on the stock switch, one that makes contact with the arm in the Forward position, and one in the Reverse position. Just use a multimeter to check for continuity as you switch the handle. Just be sure to use terminals that are not active at the same time!

I have attached a drawing of a typical drum switch, and if yours is similar, you would wire it as follows. (It looks to me like your switch is upside down, compared to the drawing.)


12v to terminal 3
Fwd to terminal 4
Rev to terminal 1

Connect the Shields of both cables to the ground at the VFD ONLY!!  Do not connect the shield at the switch.  This would create a ground loop, and could damage the drive.  Same goes for the motor, when you wire it.  (And shielded cable is not REALLY necessary if you do not have electronics nearby, eg a computer)

Also, ignore the third vertical set of terminals, the set without screws. This set should not get wires, as the are only there for ease of construction. 

-Cody


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## woodtickgreg (Jul 7, 2013)

Ok so your saying that the 12v is used to send a signal to the switch and back. That would mean I need a 3 conductor wire that is shielded, the o.m. called for a 2 conductor, all very confusing. To find which terminals on the switch are used I would touch #3 with the meter and move switch to forward and see which terminal has continuity? And same for reverse I assume.


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## Codered741 (Jul 7, 2013)

woodtickgreg said:


> Ok so your saying that the 12v is used to send a signal to the switch and back. That would mean I need a 3 conductor wire that is shielded, the o.m. called for a 2 conductor, all very confusing. To find which terminals on the switch are used I would touch #3 with the meter and move switch to forward and see which terminal has continuity? And same for reverse I assume.






This should be what you find with your multimeter.  

Flip the switch into forward, and measure between the center terminal, and the one to the left, as shown in the photo.  This SHOULD show continuity.  Measuring between center and down left, there should NOT be continuity, with the switch in forward.  

Flip the switch to reverse, and the readings should follow.  Center to left should NOT connect, and center to down left SHOULD connect.  

You don't really need to get 3 core wire, unless you really want to.  There should be no issue making two cable runs, and just leaving one conductor unused. Just make sure to ground both shields to the drive.  

-Cody


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## woodtickgreg (Jul 7, 2013)

Codered741, you da man! That is exactly what I was needing, this helps a great deal. THANK YOU! I found the wire for the switch, now just have to find 14/4 awg shielded for the motor, I only need about 10' of it, having a hard time finding it. 
Since I have your attention........what do you think about a twist lock plug in the output 3 phase wire? Would that kill the shielding?


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## Ulma Doctor (Jul 7, 2013)

Hi Greg,
shielding is an outer wrap of material around wiring that keeps stray electromagnetic signals from interfering with a circuits purpose.
as Cody said earlier, unless you have some serious interference from other electronic devices, shielding out your 3 phase is not necessary, and will be quite expensive to find sufficient cable that is shielded.
i would more worry about the input side for shielding, your 3 phase motor will not care about shielding.
the freq controller won't care either about the output.
I use twist locks on shielded equipment all the time, no danger there!!!
mike)


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## DMS (Jul 7, 2013)

woodtickgreg said:


> Since I have your attention........what do you think about a twist lock plug in the output 3 phase wire? Would that kill the shielding?



I'm assuming the receptacle is going to be in the VFD enclosure (or real close). If so, you should be ok, just make sure to connect the shield to the ground in that cabinet. Do not connect the shield at the other end. The cabinet should have a good protective earth, nicely terminated.


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## Codered741 (Jul 7, 2013)

Greg,

Glad I could help! 

As I said earlier, shielding is really NOT necessary for your cable, input or output, unless you are running other sensitive electronics nearby. 

That being said, if you wanted a plug between the output of the VFD and the motor, just get a connector with an extra pole, and connect the shield through that. Yea there will be a little EMI leakage at the plug, but your drive won't put out enough to affect anything. (Unless your computer is sitting on the VFD, in which case you need a better place for the computer). 

McMaster-Carr has 14/4 shielded cable that would work, but it is not cheap.  #9936K75.  

I personally run all of my machine VFD's with unshielded cable, and have never had a problem. With CNC machines this becomes an issue, because electronics are necessarily close to the machine, and often the cables need to be bundled together. 

And make sure that the VFD is OFF, BEFORE you unplug the motor. Failure to do so can damage your drive. 

-Cody


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## woodtickgreg (Jul 7, 2013)

Thanks for all the advice guys! The only reason I was talking about using shielded wire was because that's what the O.M. called for. I guess these vfd's are very sensative to voltage leaks etc.  At least that's how I read it, but you guys are saying not to be to concerned with it. I will not be running the wires in a conduit as I may need to move the lathe from time to time. I was going to run a ground wire from the motor housing to the vfd ground termination point. I purchased a 4 pole twist lock plug set and I was going to use that for the motor power cable between the vfd and the motor. These vfd's have got to have the crappiest manuals and instructions I have ever seen, LOL.
Input wires, got it.
output wires, got it.
switch wires, got enough to figure it out I think, the switch diagram was a big help!
God help me when I try and wire a variable speed pot, LOL.
Oh well this is all new to me, I can wire a house no problem, but figuring out electronics.........still learning I guess.
Thanks to all for your help and patience with me on this important step.


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## woodtickgreg (Jul 9, 2013)

I went to a large electrical supply house by me that has everything electrical, from small to industrial. They did not have the 14/4 shielded wire either, so based on the advise of others here I purchased a very good rated at 600 volt 14/4 rubber covered wire for the 3 phase power cord from the vfd to the lathe. One other question I have is should the power cord be grounded at the vfd and at the motor also? I think it should be. The motor was not grounded when I got it and I was going to ground it with one of the cover screws. The reason I ask this is the O.M. states that the shielding should only be grounded at the vfd.


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## Codered741 (Jul 9, 2013)

That's correct Greg.  

The shielding should only be grounded at one end, but the motor should have a dedicated safety ground regardless.  You said yours did not have one, neither does mine.  Just find a screw or bolt close to the motor, mounting bolts work fine, and attach it there.  Make sure that you have a good connection, preferably using a star washer to really get the best contact.  

You wont have any problem running without the shielded wire.  

-Cody


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## woodtickgreg (Jul 9, 2013)

Awesome! Thanks that's what I thought, gonna go play with some wires now.


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## woodtickgreg (Jul 10, 2013)

The vfd is wired and so is the switch, a little fiddlin with the parameters and she's up and running and uses the original switch for forward, off, reverse. 
I do have a couple of questions though....what a surprise. I have the upper set at 60 hrtz and the lower set at 50, can the lower be safely set any lower or should I leave it there? 
Second, Unless I pull the disconnect the vfd is always on, is this normal?
I do see myself getting a speed pot for this thing, it just works too good. I ran it for about a half an hour and it didn't even get warm.


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## Codered741 (Jul 10, 2013)

Hey Greg, 

You can safely set the minimum frequency at 0. It is generally not recommended to run motors for long periods at very low frequencies, due to overheating, so I usually use about 20-30. If you leave the minimum too high, you lose the benefits of a VFD. 

And yes, it is completely normal for the VFD to stay on, even when not running. Just power it up via the disconnect when you start working, and shut it off when you leave. Avoid repetitive cycling on and off. 

-Cody


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## woodtickgreg (Jul 10, 2013)

Codered741 said:


> Hey Greg,
> 
> You can safely set the minimum frequency at 0. It is generally not recommended to run motors for long periods at very low frequencies, due to overheating, so I usually use about 20-30. If you leave the minimum too high, you lose the benefits of a VFD.
> 
> ...


Thanks for all your help Cody, I really appreciate it, vfd's are all new to me, but man are they cool! I'll get the lower range reset a little lower. So if I pull the disconnect it won't loose it's memory?


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## Codered741 (Jul 10, 2013)

No problem Greg!  I'm sure that I am going to have a bunch more questions as I get further into my rebuild. So I figure that I'm just paying you back ahead of time. 

Your VFD should not lose its memory when you shut it off, but check the manual for any thing like that. 

-Cody


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