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VFD Wiring

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Ghosty

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Hi All,
I am in the process of fitting a VFD and motor to my lathe, what type of wire is required for the VFD to motor connection? I have been told that you require special VFD wire for it, is this correct.

Cheers
Andrew
 

G54AUST

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'Evening Andrew.

Yes, there is a special shielded wire to use. It's referred to as Shielded VFD cable. Your local elec supplier (Middy's etc) should be able to supply in cut length to your requirements. You'll also need the cable ends to allow EMI earthing etc.

If you local can't supply, try Peter at Homann Designs down here in Melbourne. VERY helpful bloke.

What VFD did you choose ???


Kind Regards,

Trevor,
Melbourne, AU.
 

Ghosty

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Trevor,
Thanks, I had already ordered the VFD motor cable just has not arrived yet.
Got this combo(VFD & motor combo) Found on Flebay, Item # 183795572871, Have set up on bench to setup VFD.
Lathe that I have (al250) only has a top rpm of 1600, most work I do in under 25mm dia, so I would like to up that to around 3000rpm, this was the best way to go, I had a Seig S3 lathe that was 2500rpm, just a little small for some of the items that I swing at times.
Cheers
Andrew
 

ignator

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As long as the VFD to motor cable length is typically shorter then 6 feet (1.8m) you do not need special EMI cabling. I have 9 VFDs in my home shop, and I've never experienced EMI/EMC issues. These become a problem with long wires between the motor and VFD. You do not want to mount the VFD directly to the machine if there is vibration transmitted to the VFD during heavy cuts. The VFD components will suffer from vibration failure. I have all my VFD's mounted on the wall directly behind the machine.
If you're remoting start/stop/FWD/REV and speed control, again short lengths of wire limit EMI antenna length. The potentiometer connections may need shielding, it all depends on the resistance of the pot. Most VFDs call for a 1000 ohm pot. This is low enough resistance to limit RF interference, that and keeping it away from the power and motor connections.
I could not find your VFD using the auction number listing.
 

Ghosty

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ignator, Thank you for the info, I wont be pushing the setup to the max, just need to up the speed toaround 3000rpm max on the head stock. The VFD is mounted on the wall just above the lathe, wiring will be about 4 foot in length, and I will be using remote switching, Pot wiring is shielded. The item # is for AUS Bay site, You can try the below.
183795572871 | eBay
Cheers

Andrew
 

TonyM

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Remember if you do use proper shielded cable (not armoured which is ineffective at shielding), only connect the shielding to the earth at one end. I am not sure if it is better at the motor or at the VFD but it must not be both.
 

xpylonracer

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Like TonyM above I always believed the screen connection should only be at the VFD end but not at the motor, it is best to check what the VFD manufacturer recommends as some now state to connect the screen to earth/ground at both ends.

xpylonracer
 

ignator

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ignator, Thank you for the info, I wont be pushing the setup to the max, just need to up the speed toaround 3000rpm max on the head stock. The VFD is mounted on the wall just above the lathe, wiring will be about 4 foot in length, and I will be using remote switching, Pot wiring is shielded. The item # is for AUS Bay site, You can try the below.
183795572871 | eBay
Cheers

Andrew
Ebay has some sort of filter preventing me looking at this. I did try your auction number before from the AU eBay site, with the same results as your link, not found. I'm guessing that this can not be shipped to the States, and eBay is looking at my cookies, even when I sign out.
I assume this is some sort of 50hz motor ~750watts with a matched China made VFD. My first VFDs 15 or so years ago were of the standard type. But I learned these did not allow low RPM operation and produced a cogging operation. For low speed high torque operation VFDs need to be of the Sensorless Vector design. All this really is, improved software that they charge more for.
If your drive permits the display of motor RPM vs HZ. You key in the motor RPM to spindle ratio, into the correct program parameter, and turn that display on, you can direct read the spindle RPM. That works if you leave the belt setting to one configuration. I found this to be the middle speed setting, which will give torque over a wide range. Also most of my motors are 4 pole, so I allow double the HZ operation (in your case 100Hz) as the rotor in these small motors can run faster then the 2 pole speed.
The only combo packages I could find were for spindle motors (CNC router), or stationary belt sander motors.
 

awake

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A word of caution that you've likely already thought about: You are talking about nearly doubling the speed of your lathe. Are the bearings up for that? What about the chuck? Not all chucks can be safely spun that fast. :(
 

Ghosty

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Ebay has some sort of filter preventing me looking at this. I did try your auction number before from the AU eBay site, with the same results as your link, not found. I'm guessing that this can not be shipped to the States, and eBay is looking at my cookies, even when I sign out.
I assume this is some sort of 50hz motor ~750watts with a matched China made VFD. My first VFDs 15 or so years ago were of the standard type. But I learned these did not allow low RPM operation and produced a cogging operation. For low speed high torque operation VFDs need to be of the Sensorless Vector design. All this really is, improved software that they charge more for.
If your drive permits the display of motor RPM vs HZ. You key in the motor RPM to spindle ratio, into the correct program parameter, and turn that display on, you can direct read the spindle RPM. That works if you leave the belt setting to one configuration. I found this to be the middle speed setting, which will give torque over a wide range. Also most of my motors are 4 pole, so I allow double the HZ operation (in your case 100Hz) as the rotor in these small motors can run faster then the 2 pole speed.
The only combo packages I could find were for spindle motors (CNC router), or stationary belt sander motors.
Here is a photo of the VFD mounted on wall. yes the new motor is 4 pole
 

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Ghosty

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A word of caution that you've likely already thought about: You are talking about nearly doubling the speed of your lathe. Are the bearings up for that? What about the chuck? Not all chucks can be safely spun that fast. :(
Yes, this is some thing that I will keep an eye on, looking to replace the bearings with taper roller at some stage.
 

ME2

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Just another thing to be aware of is that if you have a belt drive from the motor, it may whip and will tend to wear out quicker. I found both of these to be an issue when l ran above base speed through my VFD.
Cam
 

dazz

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Hi
I replaced the Vee belt drive with a poly-vee to avoid problems with belts. The second part of the drive still uses a poly-link belt.
Denford VFD retrofit.
If you can spare the cash, try and use an industrial grade VFD. Once you get over the one-off damage to the bank balance, it is all good news.

Dazz
 

Shopgeezer

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I am looking at this VFD because I like the fact the control board snaps out and can be remotely mounted. It also has a pot built in.


This motor is also attractive for price.


But I am getting scared a bit from the various subteties I am reading about on this forum. Low speed torque, vibration, cogging, compatibility of the VFD software with the motor, motor design problems and so on won't reveal themselves until the units are on the bench and the money is spent. Are there any hints from the ads about compatibbility of these products. Contacting the vendor is useless. The sell a big list of products and don't know anything about any of them.
 

Iampappabear

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This might be the place for this we question. I have often pondered putting one VFD on the wall and running all my machine from this one source, just need to have a plugin potentiometer at each machine. Rev counters are real cheap these days on eBay so every machone could have one. Thoughts anyone?
 

xpylonracer

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Only worth doing if all motors have the same FLC and you want all characteristics to be the same for all machines.
Also in addition to a plug-in pot you will need stop/start provision at each machine.

xpylonracer
 

Iampappabear

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Hmm.... good point, my thoughts were to install VFD to suit largest MTR but then I guess no real protection for smaller MTRs. I have individual VFDs on each of my machines but was discussing this with someone who has 5 (dropping down to 3) Bridgeport mills in a row and he only ever uses one at a time.
 

ignator

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I am looking at this VFD because I like the fact the control board snaps out and can be remotely mounted. It also has a pot built in.


This motor is also attractive for price.


But I am getting scared a bit from the various subteties I am reading about on this forum. Low speed torque, vibration, cogging, compatibility of the VFD software with the motor, motor design problems and so on won't reveal themselves until the units are on the bench and the money is spent. Are there any hints from the ads about compatibbility of these products. Contacting the vendor is useless. The sell a big list of products and don't know anything about any of them.
Shopgeezer: I've never had a problem with any of the 9 VFDs I've installed except 1, and that was off eBay from a China seller with the Huyang (can't recall spelling), where the first one had a rectifier capacitor blow up, so I returned that, and they sent a replacement that sits on the shelf, as a memory to not buy that namebrand.
My point about cogging was from the first VFDs I purchased that were Teco FM100. They are not of the vector design.
I see your in Canada, I don't know if this vendor will ship there, but they have packaged motors and drives. They are in New Jersey. This package is a 1.5HP motor with a 2HP Teco 510, that is a vector type drive;
I've also had good luck buying used drives off eBay, BUT make sure they are 200V class, as the 400V class will not work in a home shop. Also make sure you can download a manual, as there are some vendors that remove manuals from their web site that are no longer in production (e.g. Rockwell Automation formerly Allen Bradley). And there are some larger drives that will not work unless powered from 3 phase, as they detect phase loss. Again the manual will tell you if this feature can be turned off. Once you get above 3 HP VFD size, you need to derate it to half the horsepower, this is from the limit of the input rectifier diodes, where powering off single phase can exceed their current capacity. I have a 7.5HP lathe, that I'm using a 10HP VFD to power and have never had an issue, as I never do crazy depth of cuts with high feed rate, and high spindle RPM. I have a table saw this is also 7.5HP and powered with a 10HP drive. Otherwise the Milling machines, small lathe, drill presses, bandsaws are all 1-2HP size motors. I've removed single phase motors and replaced them with 3phase because of the variable speed operation. On a drill press these are the sweetest thing when you can dial up the spindle RPM to match the SFPM of the cutting tool. Same with the lathe.
I have a VFD powering one motor from the early 1940s on my horizontal mill. In the early days of VFDs, the edge rate of the square wave pulses were so fast that they caused large voltages to develop from the inductance. This problem is gone as they control the edge rate on drives, to minimize the problem. If you have an old motor, and the insulation is of very degraded quality, you may end up with a short of a winding to chassis. But that old of a motor probably would fail with your normal power input.
The links to Amazon for motor and VFDs looks like a good setup. The inverter duty is mainly better insulation quality on the motor windings.
The other quality of VFDs, they produce a soft start, so there is no locked rotor amp surge. As well they control both acceleration and deceleration speed. I set up the deceleration to coast to stop. It can decelerate fast enough to enable a thread on lathe chuck to spin off. The default I've seen in my various drives is 5 seconds accel/decel.
 

Shopgeezer

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Ignator that package deal looks great but in US dollars so a big hit on currency exchange as well as very expensive shipping. The nice thing about Amazon is the free shipping. I’m tempted to go with that motor and VFD deal. I can buy local for three times that much. Probably smart to do that for the support and warranty but just too much cash.
 

ignator

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Ignator that package deal looks great but in US dollars so a big hit on currency exchange as well as very expensive shipping. The nice thing about Amazon is the free shipping. I’m tempted to go with that motor and VFD deal. I can buy local for three times that much. Probably smart to do that for the support and warranty but just too much cash.
I think the Amazon motor and VFD will work perfect. Your just not going to need support. And if you get this installed and it fails within the Amazon time period, you either send it back as junk, or get a replacement. But It looks like a quality unit.
The photo you have of your drive, I could not see the model number. I was going to look that up to see if it is a vector drive, and how good the manual is, and try point to programming parameters that enable the spindle speed readout direct on the LED panel display. It may not have this.

So assuming you integrate this with your existing lathe switches, that may be the only difficult part. The ONE RULE is never switch the output of the VFD to the motor, EVER. It is hard wired from the VFD to motor terminals. All control is either from the front panel of the VFD, or a remote start stop FWD/REV switch box.
The reason is if you interrupt the connection when there is a large current flow, the inductance from the motor creates a huge surge voltage that can damage the transistor switches in the VFD.
The lathe's switches can be integrated to do this function of controlling discrete input connections of the VFD.
As a side note, I grew up in North Dakota, I remember the exchange rate being the other way, $0.82 Canadian to $1.00USD. That NAFTA trade agreement worked well. ;)
 

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