I need help on a VFD and motor

[rodney mitchell]

I have read post after post on the subject and am more confused than ever. I think I am electrically challenged. I need a variable speed set up on a Coote belt grinder and don't know what to get.
I do know I want a 1 1/2 to 2 HP motor which I hope to find used. (money is a big consideration in this project). But I don't know if I need a DC motor, a 3 phase motor, an inverter-duty motor; 3600 rmp, 1725 rpm, needless to say I am confused. Then on to the VFD, what kind to buy and where? Thanks for any help.

Rodney Mitchell

[Kyle Kraft]

Rodney,

I am not a licensed electrician, but I have done multi-craft industrial maintenance for nearly two decades. I got a Bodine VFD at a trade show in Chicago a few years back as a sample. It is rated for a 2hp 3ph. AC motor, you wire it up to 230v single phase and it provides an output for a 3 phase motor. If you have experience with motor controls, start/stop circuits, and industrial wiring, you should be able to "read and do" with the instructions that come with your VFD.

You should be able to come by a 1.5-2hp 3ph AC motor without too much trouble as they are relatively inexpensive and there is really no market for used motors under 20 hp. It usually costs nearly as much for a new motor as to rebuild an old one.

Good luck!!

[rodney mitchell]

Thanks Kyle, anyone have any sources for reasonably priced vfd's?

[Mike Heidrick]

www.factorymation.com (http://www.factorymation.com) is the place I bought my FM50 for my 3hp 3ph motor on my DJ30 jointer. It is great. Very simple to use.

Ebay has them cheap as well.

Need to know the motor you get first and then get the VFD sized to match.

[Richard Butler]

Rodney,

I am not a licensed electrician, but I have done multi-craft industrial maintenance for nearly two decades. I got a Bodine VFD at a trade show in Chicago a few years back as a sample.

Good luck!!

The Bodine drives I have seen were actually a FM50 by Teco/Westinghouse.

[Mike Heidrick]

I can help once you pick out a motor.

A few questions:
Are you sanding wood or metal?
How are you mounting this sander?

TEFC sized to match - .5 - 1.5hp will be MORE than enough for that sander. Call the company and see what pully you are getting and ask what rotational speed they recommend for the motor you buy.

Good news is if you get 3450 rpms we can slow them down with the VFD. 1725rpm should be more than fine as well. Consider your mount.

What pulley will you install on teh motor. What is the diameter of the mounting hole for this pulley?

There is a 1hp baldor brand new on ebay for $50 plus shipping.

So get a 220V, 1hp, 3phase 208-230Volt motor in the frame size that works best for you, in 1725 or 3450 rpm, with a shaft that fits a pulley you can buy.

The wiring we can work with you on.

[Randall Frey]

Hey Mike, not to take over the thread but, can you elaborate on the VSD for your jointer? I have not heard of slowing a jointer. How does it work and what applications do you reduce speed?

[Mike Heidrick]

I do not use the VFD to slow the speed of my jointer. I do use the slow start (3 sec to full power) and slower stop (5 sec to power off). It helps on amp draw. I am using it becuase it was the quickest way ti get my jointer up and running full power as my ROC was not built yet.

The VFD does allow for variable speed and reversing of motor very easily - those features are just not as appreciated with a jointer.

[rodney mitchell]

Hey Mike thanks for the advise. I am getting the sander used and it already has a 3 step pulley system on it, but I need the capability to slow it down to a crawl without losing any torque. It will be used for profiling steel (stainless and carbon) and for sanding bevels in the steel. Also it will be used on mammoth ivory and some exotic woods like cocobolo and bocote. It is already mounted on a stand with the motor below the sander. It currently has a 1 HP motor, but l do need the variable speed function to be able to sand very slow with some of the finer grit paper. So it sounds like I need a 220 3 phase, speed is not that important, and a vfd to match. Two questions, I have read that some vfd's will not deliver the stated HP of your motor, ie: if you have a 2 HP motor, you may only be getting 60% of that HP when using a vfd. And, what about a Nema 1 vs a Nema 4 vfd? The Nema 4 is made for a dirty environment, but is more expensive. Is that something to look for?
I know that this is not really the appropriate forum for my problem, but being a member here I know that there are a lot of ya'll with vfd experience and I appreciate the help.

Rodney

[Richard Butler]

Hey Mike thanks for the advise. I am getting the sander used and it already has a 3 step pulley system on it, but I need the capability to slow it down to a crawl without losing any torque.
Rodney


Rodney,

If you are looking to slow down a motor to say 60 RPM (1 rev per second) for example, and have full power, then there are considerations to have be taken into account. To achieve that level of performane using VFD technology requires careful selection of the drive and motor.

What you have to do is to fully qualify your requirements. What is the lowest RPM that you need? How much power at that RPM? What are the pulley diameters? What is your budget?

Once all of the requirements are known, then the engineering can begin. Without them, serious discussions are a waste of time.

[Steve Rowe]

Hey Mike thanks for the advise. I am getting the sander used and it already has a 3 step pulley system on it, but I need the capability to slow it down to a crawl without losing any torque. It will be used for profiling steel (stainless and carbon) and for sanding bevels in the steel. Also it will be used on mammoth ivory and some exotic woods like cocobolo and bocote. It is already mounted on a stand with the motor below the sander. It currently has a 1 HP motor, but l do need the variable speed function to be able to sand very slow with some of the finer grit paper. So it sounds like I need a 220 3 phase, speed is not that important, and a vfd to match. Two questions, I have read that some vfd's will not deliver the stated HP of your motor, ie: if you have a 2 HP motor, you may only be getting 60% of that HP when using a vfd. And, what about a Nema 1 vs a Nema 4 vfd? The Nema 4 is made for a dirty environment, but is more expensive. Is that something to look for?
I know that this is not really the appropriate forum for my problem, but being a member here I know that there are a lot of ya'll with vfd experience and I appreciate the help.

Rodney
Rodney,
I added an AC Tech drive (NEMA 4 enclosure) to a 2HP Jet 20" disc sander because the 1800 rpm nominal was just too fast. I was concerned about dust collecting in the electronics so went with the NEMA 4. It was actually cheaper to get the NEMA 4 model rather than purchase a separate enclosure to protect the electronics from dust and worry about ventilating, filtering, and cooling the unit. I normally run this machine around 750 rpm. I set this up with separate switches mounted directly to the machine to start, stop, increase/decrease speed, and reverse. The manuals are very good on programming and wiring up VFDs. I have not noticed any reduction in power even at slow speeds but this is a subjective assessment.

Expect some setup troubleshooting depending on your application. The disc sander has large momentum and I was getting drive faults when I would shut the machine off. The manufacturer was no help and did not respond to my email questions. I purchased from a local distributor and they knew nothing about VFDs - apparently they just sell them. I ended up figuring it out on my own and just increased the ramp down time - problem solved. There is an annoying whine that comes from my motor during operation with a VFD that wasn't there before VFD and I suspect this is related to not having an inverter duty rated motor.

The best price I have found on VFD is AutomationDirect.com and apparently they actually know something about the product. I would have purchased from them but they did not have a NEMA 4 model.

Steve

[Richard Butler]

The variable speed capabilities that a VFD gives are very handy on a bandsaw, drill press, lathe, scroll saw, and occasionally on the tablesaw. The dynamic braking in very handy on almost all tools.

[Rick Lizek]

You will most lilely have to add a gearbox to really slow it way down. Thw VFD will not have full torque if it slows down too much. You can buy gear motors but they will bump up the price a lot.

[Brian Weick]

you will have to get a VFD that is twice the hp rating of the motor for starters,ie-1,5hp motor ~ 3hp vfd. I would get an inverter duty motor this will allow for variable speed without having a lot of motor windings getting hotter than usual. I have a 3hp Baldore inverter duty motor and a Yaskawa 7.5 hp rated VFD with all the bells and whistles on my Oliver 20C lathe. There is absolutely no heat from my motor windings at any speed dialed in from the vfd~ it is an amazing piece of technology. I have run the lathe at 1.0 (ranges from 1-60 hertz) with no loss of torque. You have to overrate the VFD because you are going from single phase 220 to 3 phase 220 and you are missing the third leg on the in-feed to the vfd ~ hence that is why any electrical engineer will always tell you to get twice the hp rating or you can damage the motor or the unit. I did a lot of research into this before I made any VFD purchase and "ALL OF THEM" told me the same information. I hope this helps and I wish you good planning with your project, there is no luck with this :)
Brian

[Mark Hubler]

I have read post after post on the subject and am more confused than ever. I think I am electrically challenged. I need a variable speed set up on a Coote belt grinder and don't know what to get.
I do know I want a 1 1/2 to 2 HP motor which I hope to find used. (money is a big consideration in this project). But I don't know if I need a DC motor, a 3 phase motor, an inverter-duty motor; 3600 rmp, 1725 rpm, needless to say I am confused. Then on to the VFD, what kind to buy and where? Thanks for any help.

Rodney Mitchell

A few things to know:

1. When looking for a 3 phase motor, pay attention to the insulation class of the motor. To be inverter duty, it should have class "F" insulation. The voltage produced by a VFD is not a true sine wave; it is a series of DC pulses, which makes more heat.

2. If you decide to buy a new motor, contact the guys at www.dealerselectric.com . I bought a 2hp motor and teco/westinghouse FM100 vfd from them a couple of years ago; great service and great products. If you get an FM100, the manual from Bodine is written a little clearer.

3. There is a lot of discussion about VFD's at the practical machinist forum. Search for posts by Forrest Addy http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi

4. VFD'd are very easy to wire; two power wires in, three power wires out. Even the low voltage controls (optional) are fairly straight forward.

[Richard Butler]

Rodney,
There is an annoying whine that comes from my motor during operation with a VFD that wasn't there before VFD and I suspect this is related to not having an inverter duty rated motor.

Steve


Actually it is the carrier frequency that you are hearing. Raise the frequency up and it will go away. Read the manual regarding carrier frequency.

Factorymation has the best prices I have seen.

[Richard Butler]

you will have to get a VFD that is twice the hp rating of the motor for starters,ie-1,5hp motor ~ 3hp vfd.... I did a lot of research into this before I made any VFD purchase and "ALL OF THEM" told me the same information. I hope this helps and I wish you good planning with your project, there is no luck with this :)
Brian


That is odd. When talking to Teco/Westinghouse they said that a 2hp motor and a 2hp VFD were a good match. I specifically asked them about a 2hp motor with a 5hp VFD and he said it was ok to do that but that I would be spending a lot of money for no good reason.

As far as inverter class motors go, the necessity of an inverter class motor depends on application.

Here is how i look at it.

If I spend $40 for a 3 phase non-inverter classed motor and it lasts (which in all likelyhood it will) then I will have saved a bundle of money. Most VFD related motor failures occur at 460VAC, not 230VAC. Odds are that my motor, like many motors, will last indefinitely on a VFD. If not, then I am out $40 which is the price of a good steak dinner.

[Brian Weick]

Rob,
To the best of my well spent time researching this because I did not want to start with a defective application first of all and then have to eat the cost of a VFD because I failed to ask the proper questions and do my homework,which is why I have a 220v single phase into a 7.5hp vfd 220 3 phase out powering a 3 hp inverter duty (f-class) 220v 3 phase electric motor. If you are converting 220v single phase to 220v 3 phase via a VFD you need to dbl the hp rating of the vfd , but not to exceed the amperage of the vfd as well in order for the VFD to operate efficiently. I have a massive lathe that operates in conjunction with a step down transmission with incredible amounts of torque at low speeds as well as reaching 3500 rpms, now maybe your application is different. IF you are going 220v 3 phase in - that is an entirely different application and you can match the hp rating to the motor and it will perform flawlessly providing the amperage ,again does not exceed the stamped specifications on the VFD.

NOTE: If you are using a VFD -(f class rating is highly recommended) This is what I have learned from talking directly with the vfd manufacturers, I don't know who you spoke with or if they failed ask you important information about your application , but the rule of thumb when discussing VFD applications is F-class inverter duty motor. If you have a lot of heat on the windings after a short running- there is a problem with the electrical application at hand. I have run my lathe for 2 hrs straight at full capacity doing smaller turnings and the motor is not even warm- it has never gotten warm since I have updated the Oliver lathe ~ that gives me a piece of mind- In my line of work , quality and reliability is what I am aiming for ~ it's not worth it ti me to gamble by saving a few bucks - that's just me Rob, I am glad yours works for you and I hope it continues to perform as good as the day you installed it :)
Happy Turnings
Regards,
Brian.

[Richard Butler]

I hope it continues to perform as good as the day you installed it :)
Happy Turnings
Regards,
Brian.

Brian,

What you may have failed to realize is that there are VFD's out there that are rated for single phase input. The upshot is that you don't have to "derate" the VFD for the motor in question.

Case in point:

The Teco FM100.
The FM100-203 is rated for 3hp with single phase or three phase input where the FM100-205 is only rated for 3 phase input.

The bottom line is that for those VFDs that are spec'd at single phase input will produce enough 3 phase current to drive their rated HP load.

Cheers.

[Brian Weick]

Talk to an electrical engineer- It "does" make a difference" Otherwise I would be toasting marshmallows on Baldor ~ I have a VFD that will take in 3ph or single ph 220 ~ but that does not create the same application when single phase is used as the input source on that type of electrical hookup.
Happy Turning
Brian