VFD help needed

[mark kosse]

Howdy all,

I've never used a vfd. I picked up a late 60's 2hp PM 66 today and need a vfd to run it. Looking at eBay I see 2hp vfd's in both 110 and 220 volts. I never knew a vfd could be run on 110v, or is it too good to be true. It really would be better for me right now to have it run 110v.

Can a vfd run any hp below it's stated rating? Can a 2hp vfd run a half hp motor?

thanks, mark

[Alan Schaffter]

Howdy all,

I've never used a vfd. I picked up a late 60's 2hp PM 66 today and need a vfd to run it. Looking at eBay I see 2hp vfd's in both 110 and 220 volts. I never knew a vfd could be run on 110v, or is it too good to be true. It really would be better for me right now to have it run 110v.

Can a vfd run any hp below it's stated rating? Can a 2hp vfd run a half hp motor?

thanks, mark

You haven't said, but is the PM 66 motor 3 phase? If not, it won't work with a VFD. Yes, a VFD will run any 3 phase motor below and equal to its rating. The rating of some, not all VFD's must be de-rated, if powered from 110V.

[Mike Henderson]

A standard 15 amp 120V outlet will not supply enough power for a 2HP motor, especially after you add the losses of the VFD. You'd need a higher amperage 120V circuit, but a 240V circuit would be better.

All this assumes that the PM has a 3 phase motor.

Another alternative that might be about the same cost is to see if you can get a 2HP single phase motor for the saw.

Mike

[Matt Day]

Check out the teco models at Factorymation. I have the 3 hp fm50 for my bandsaw for about $200 and it works great.
I believe the vfd can power any Motor, rated higher or lower hp, but the max it can power is the rated amount. Not sure on that though.

[John McClanahan]

Read the specs close. I doubt you can get a VFD for 110v in and 220v 3ph out for a 2 hp motor. I think you will find that 110v VFDs top out at around 1 hp, at least from what I've found.


John

[mark kosse]

Thanks for the replies. The saw is 3ph, which is why there is a need for a converter. I guess I'll wait until I get a better service run to my shop before I make any decisions. I have other table saws running so it's not needed at the moment.

[Josh Bowman]

I agree that 1 hp is about all you'll do with 110 volts. Check out Dealerselectric.com. I've bought 2 vfd''s from them with the 3 phase motor. Good help and Tech support. I think they're the cheapest for the package.

[Doug Ladendorf]

I have not used them but my understanding is that the cheap VFD's on eBay are not worth the few dollars saved over the ones Matt and Josh have mentioned. For 2HP you really should go with 220v even if you could get it to work on 110v.

[NICK BARBOZA]

Call Wolfe Automation and talk to Scott. He just set me up with a new VFD for my Delta lathe

http://www.wolfautomation.com/
1800 325 9653.

[Chris Parks]

I have not used them but my understanding is that the cheap VFD's on eBay are not worth the few dollars saved over the ones Matt and Josh have mentioned. For 2HP you really should go with 220v even if you could get it to work on 110v.

I can't comment on Ebay VFDs in general but the Huanyang brand has a good reputation amongst the CNC guys around the world, the only thing it lacks is a rotary speed controller that is an advantage for some applications. I sold a lot of them and have had no failures but went to a different brand due to supply issues at one stage and other advantages that suited the application we were using them for (CV cyclones). They are great on a cyclone due to low power/soft starts (16 amps on 220V maximum draw) and the ability to change the impeller speed.

[John Lifer]

I can't speak to the foreign VFDs on eBay, but the Allen Bradley units that are typically surplus are fine and usually cheaper than new. Manuals are on line so you can find right unit. You need to get the amperage of the motor and along with voltage, you match a vfd to the motor. If it is 15amps at 240 V, you need vfd that outputs that much or more. You CAN, in most cases use one slightly, read maybe an amp or so under the motor need, as the vfds usually output 15% or so over for short time. But I'd go over rated if possible. Good luck!

[Danny Barber]

I wouldn't buy any product on eBay if it is for a business use. There's so much risk involved. The factory warranty/support may not be available. You do not know how long the drive has been sitting on a shelf.

There are lot of manufacturers offering single phase input VFDs now. Take a look at AC Tech's SMVector series. It's made in the US & they have a very reasonable price point.

http://www.ctiautomation.net/Lenze-SMVector-IP31.htm

[Jim Neeley]

I deal mostly in industrial VFDs (VSD, ASD) but the ones I use have contacts in the back you can use to turn it on/off using a low power switch.

Get the manual on your VFD and check it out.

Jim

[Jeff Raefield]

I can't comment on Ebay VFDs in general but the Huanyang brand has a good reputation amongst the CNC guys around the world, the only thing it lacks is a rotary speed controller that is an advantage for some applications. I sold a lot of them and have had no failures but went to a different brand due to supply issues at one stage and other advantages that suited the application we were using them for (CV cyclones). They are great on a cyclone due to low power/soft starts (16 amps on 220V maximum draw) and the ability to change the impeller speed.
Wow, Huanyang VFDs are the absolute WORST brand on the market in my opinion. I've taken a few apart, they are pure unadulterated junk, ANYTHING would be better than a Huanyang. Many of the FleaBay resellers are now leaving the name off of their listings because the reputation is so bad. I don't know why the CNC guys seem to like them, probably the price. But I tell people to steer clear, it's not worth it if you have to replace it every 3 months, warranty or not (and usually the FleaBay resellers disappears once they sell out their lot). Teco, Hitachi, Lenze / AC Tech are all good brands with low cost options, anything but Huanyang...

How the single phase input on VFDs work is this; ALL VFDs work by converting the AC to DC, then re-converting the DC back into something that looks like AC to a 3 phase motor. On the conversion (rectifier) side, the drive really doesn't know or care if the power is single phase or 3 phase, that's why they are a good way of using 3 phase motors with single phase services. But what DOES matter is the current rating of the components, and the "ripple" on the DC bus created by the rectification. When you rectify single phase, there is a LOT more ripple on the DC bus, which can damage the transistors in the drive that make the output for the motor. So to smooth out that ripple, they use capacitors. For a VFD to be used on single phase, it needs MORE capacitors than one that takes 3 phase; at least twice as much. So that's why you will hear that you can run ANY VFD with a single phase input, by doubling the size. It gives you more capacitance, plus it increases the current rating of the rectifier components as well (because they pull 173% of the motor current, based on the difference between single phase current and 3 phase current being the square root of 3, 1.732).

On the 115V versions they do it a little differently, using a special tricky little "voltage doubler" on the DC circuit. So it takes in 115VAC, rectifies it to 162VDC, then doubles it to 325VDC to feed to the transistors, which produce 230VAC for the motor. But the components to pull that off get really expensive and hot once you go over about 15A. So for that reason, the 115V input versions are always limited to 1HP, because a 1HP 230V motor is rated for 4.2A, but that means it needs 4.2 x 1.732 or 7.27A, x 2 (because it's 115V) = 14.54A. Technically, you can't run 14.5A from a 15A wall socket outlet continuously, but that is defined as 3 hours or more, so the concession is that if you were going to fully load a motor for 3 hours or more, you would not be using a VFD, so it's allowed. BUT NO LARGER THAN 1HP.

By the way, be careful with old used VFDs on FleaBay as well. If they have been sitting on a shelf for more than a year, you need special care to "reform" the capacitors before fully energizing them, otherwise you can burn them out and fry the whole drive.

[Allan Speers]

By the way, be careful with old used VFDs on FleaBay as well. If they have been sitting on a shelf for more than a year, you need special care to "reform" the capacitors before fully energizing them, otherwise you can burn them out and fry the whole drive.

That's a bit overly conservative. Decent electrolytics can sit on the shelf for at least 5 years before any kind of leakage starts. If the unit contains cheap caps, then they should be upgraded, anyway, the same way many folks upgrade computer LCD's. If the unit is more than 5 years old, I wouldn't use the original caps even if brought up on a variac, I'd just replace them.

- But it's somewhat moot. The price of VFD's has come down so much in recent years, used ones typically sell for more than the current new TECO's & such.

[John Lifer]

Wow, first post Rant! BTW, I own two used Allen Bradley vfds that I obtained off eBay and they have worked perfectly for several years now. The one I bought new, a teco, died after 14 months, cap crapped out and burned out board. So your take is quite wrong from my point of view. And reforming just means plugging in for a few hours bf using after storage. Can't speak of the Chinese brand....as always, buyer beware.

[Allan Speers]

Don't mean to be rude, or argue, but reforming is NOT plugging in for a few hours bf using after storage. That can cause the cap to rupture.

Reforming is done by slowly bringing up the voltage, preferably with the cap out of the circuit, and a power resistor inline circuit. I suppose MAYBE in a 1-ph motor, those caps don't see full voltage until you turn the motor on (I have no idea0 but that still would be a fast inrush of current, which could rupture an old cap. Actual reforming is always recommended. (Or again, just replace them when they get old.)

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

As for AB stuff, I'm sure you are correct that it is better made than any current import stuff, so I suppose it's worth considering. At the same time, yours is literally the first report I've seen (and I've been researching this for a few years, off & on) about a TECO going bad prematurely. The company seems to have a pretty good reputation.

One thing that can damage any VFD is trying to dynamically brake a motor which is at the VFD's rated limit, without extra resistors. From what I've read, it's a very good idea to add extras, or buy the optonal braking module if available. Perhaps this is one of the places that AB units are built better.

[Thomas Syrotchen]

Look at Yaskawa drives. You can buy them at fairly reasonable costs if you are comparing them to AB drives they are about 3/4 the cost. We use both in industrial environments and the Yaskawa drives have proven to be more reliable.

[Bob Burk]

I'm currently running my Uni. off of a TECO FM50. The saw has a 3hp/3ph motor. The vfd is being powered from 220v single phase. No real evidence of power loss to the saw.

Just my .02 cents.

Bob

[Allan Speers]

I'm currently running my Uni. off of a TECO FM50. The saw has a 3hp/3ph motor. The vfd is being powered from 220v single phase. No real evidence of power loss to the saw.

Just my .02 cents.

Bob


Bob, I'm considering getting a few TECO's, as the price is excellent and they are sold by several very reputable USA dealers. - But surely they are made in China or similar. Can you say anything as to the quality of the components, and basic build quality? (solder joints, etc.)

[Mike Heidrick]

I run a fm50 on my 12" jointer. Have since 2006 and it has been fine. No solder joints have failed but it is mounted right side up. J/k.

If I bought one today for the jointer i would buy a wj200 hitachi as the braking module is built in. I use a wj200 on my cnc knee mill and it is great. I like being able to use a remote panel and have a programming interface simultaneously.

[Allan Speers]

Thanks, Mike.

[Mike Heidrick]

If you do a 3hp wj200 and resistor for breaking let me know and i can get some details on the setup.