Need VFD Wiring Help

[jteneyck]

I was up at Ken Vick's shop installing the Huan Yang VFD  on his "new" jointer.  Thanks very much Mike for the link to that U-Tube video you posted earlier; w/o it I would have scratched my head a long time to figure out that poorly written manual.  We couldn't actually put power to the motor today because the wiring in it is all decayed and it needs to go off to a motor shop, but I got the VFD installed and programmed so I thought I'd check to see if it would send power to it. 

I wired the VFD so that it's output would go through the existing on/off switch and contactor.  Didn't work.  I got an error message when I pushed Run on the VFD.  So I'm wondering how it needs to be wired so that I can use the existing on/off switch.  Can I wire the switch to the Com and Forward wiring terminals in the VFD.  I'd like to keep the existing contactor in the circuit, too, if possible. 

Does anyone know how to do this?  Thanks.

John

[Just_Dave]

You cannot interupt the wiring on the motor side of the drive, they do not like that. It would be best to wire the switch in to the drive remote start function.  Note that This function may have to be programmed. 
As for the contctor you don't need it the drive is performing the same function only better.

[EvilTwin]

The VFD wants to see a load on the output side, so when you told it to run, it tried to sense the resistance of the motor winding's and didnt see any. I always hardwire the output straight to the motor. I use a switch (usually the one originally on the machine to control the power in to the VFD. HTH.

[TDKPE]

As the others have stated, you need to wire the motor directly to the VFD. No switches. Disconnecting the motor will cause the VFD to fault out when it tries to put power to it.

You can retask the contactor to connect/disconnect power to the VFD, but that's not really necessary. I just use a toggle switch on my lathe for that purpose. Plugging and unplugging is hard on the plug, as the capacitors don't like being disconnected, and will arc a little.

Any other control, like start/stop and reverse (reversing drum switch, for instance) can usually be wired to the programmable (or dedicated, in the case of my WEG VFD) inputs/outputs, so the lathe can still be controlled with whatever was originally controlling it.

[EricU]

That manual is great, isn't it?  And I didn't know you could typeset that small, great for the bifocals set.  I have seen it as a pdf though.  As others have said, the VFD needs somewhere for the output current to go or it will fault or even let the magic smoke out.  The vendor that sold me mine sent a link to a video that went over that.  It was actually pretty good, definitely aimed at people with a very low level of understanding.

if you look for HY videos, you'll see people wiring them.  The on/off switch goes to a digital input on the drive. Of course, a lot of people are putting them on machine tools that have run/stop/fwd/reverse, and you don't want all that, just run and stop.  You need a couple of momentary switches. I'm not sure if you can use the ones from the machine.  

I wouldn't mind a contactor on the input of my VFD, but I don't have one.  I got a disconnect at the BORG instead.

[jteneyck]

Thanks everyone.  You've confirmed what I suspected - the VFD needs to "see" the motor before it will send power to it.  I wired it the way I did thinking the VFD needed to have power to it before telling it to send power to the motor.  But it sounds like it's OK to have a switch upstream of the VFD that will turn on the VFD and, in turn, the motor, at the same time?  Is that correct? 

I can certainly bypass the existing contactor.  I was just trying to take the simplest approach possible, while still allowing Ken to use the start/stop switch on the front of the machine.  I can't locate the VFD itself on the front of the machine as it will protrude out into where you are working.  It's currently mounted on the back of the machine.  It could be used as the switch where it is, but not nearly as conveniently as the original on/off switch. 

I think I understand how the remote start feature works; at least I understand from one of the videos I watched how it's used for a forward/reverse switch.  So for start/stop it should just be a matter of wiring only to the forward and com terminals with a simple switch (SPST), yes?  And then making the program adjustments, of course, so it can be used.  This may actually be the easiest approach; just bypass all of the existing controls and put a new switch on the front of the machine going to the VFD, and then straight from the VFD to the motor as you have all said.  Sound correct?  But I guess I really need two switches.  One to turn on/off the VFD itself and the other for start/stop.  

Thanks much,

John

[TDKPE]

But it sounds like it's OK to have a switch upstream of the VFD that will turn on the VFD and, in turn, the motor, at the same time?  Is that correct?  

No, that is not correct.  The motor has to be started/stopped from the VFD, using the internal controls of the VFD.  That does include a remote control connected to the control terminals of the unit, though.  But powering up the VFD will not start the motor unless it's programmed to do that (some can do that), but that's not a good plan.

. . . just bypass all of the existing controls and put a new switch on the front of the machine going to the VFD, and then straight from the VFD to the motor as you have all said.  Sound correct?  But I guess I really need two switches.  One to turn on/off the VFD itself and the other for start/stop.  

That would be the best plan.  Any switch will probably do, either sustained or momentary.  Check the programming guide, as it can probably do either.  In the case of either, you'd need another signal to stop.  For non-sustained push-button controls, you need the two inputs.  For sustained, like a toggle switch, you use only one, energize to run, de-energize to stop, and it has to be programmed for that.

[kcwoodbutcher]

I have a HY VFD on my Dewalt GE. First thing to note is not to assume all the parameters are set to the factory defaults. Mine was way off and as a result was only putting out 50 volts max. ( the dang thing actually ran on 50 volts but no power). Go through them all to be sure. If you want to add a braking function an external resistor will probably be necessary, Ebay is your friend here. The unit itself has a small braking capacity but any bigger load will disable it.

[jteneyck]

Great, thanks very much.  I think I've got it. 

Yes, when I programmed the VFD I followed the advise to first do a reset to defaults, and then I went through the parameters needed to run the motor and set them accordingly.  I have to go back and change the motor poles input from 4 poles to 2 poles, now that the motor shop verified that's what it is, and also program it for the on/off function through the COM/FOR terminals.  With that done, it should run.

Ken dropped the motor off at the motor shop today, and the guy was optimistic the wiring had degraded and not been run after that happened.  That's the way it looked to me, too, but I'm far from knowledgeable about those things.  Anyway, we're on hold until the motor gets repaired. 

More to follow when something happens. 

John

[TDKPE]

I have to go back and change the motor poles input from 4 poles to 2 poles, now that the motor shop verified that's what it is . . .

Just so you know, it's either 2-pole, 4-pole, 6-pole, and so on.  120 times the line frequency divided by the number of poles gives the synchronous speed, so 120 x 60 (hertz) / 2 (poles) = 3600 rpm.  A 4-pole motor would result in 1800 rpm, and 50 Hz power would give 3000 and 1500 rpm respectively.  I have a 6-pole single-phase motor here that runs 1200 rpm (1140 at full load), and there are large motors that have many poles, but always a multiple of 2. 

Same with generators.  Little portables are 2-pole, and larger diesel units are usually 4-pole, though older ones (like 1940's and 50's) were 6-pole, with 1200 rpm diesels.  Big units in dams would have many poles, as they're slow turning, but still generate at 60 Hz (in North America).  But the math is the same either way.