Motor & VFD

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I don't think I explained as well as I could/should.

Design and build everything to work with a 3600 RPM motor.

Fit an 1800 RPM motor.

The 1800 RPM-rated motor can be driven to 3600 RPM by using the x2 jumper on a KBAC or by setting maximum frequency to 120 Hz on most other VFDs, making it a 3600 RPM motor.

At 3600 RPM, both the 1800-rated and 3600-rated motors will give the same torque.

EVERYWHERE below 3600 RPM, the 1800 RPM-rated motor will give more torque than the 3600. Up to 1800 RPM, the difference is double. Then it gets smaller as you get closer to 3600, where they are equal.
 
PT Doc said:
With the 2x jumper on the KB drive in place, the following happens: torque is at 50% with it is running at double the speed. At the motors labeled max rpm, the torque is at 100% that is at 60 hz. Above 60 hz, there is a linear drop from 100% torque to 50% torque at 120 hz.

If you grinder is direct drive, then you have limitations and have to make choices. With a kmg style grinder that is not direct drive, you can go 1750 and achieve the proper speed with the right sized pulley. Just some food for thought.
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MadBug said:
The 3450 will have half the torque as the 1725. Then when you find yourself running it at 50% you will have even less torque. I just went through this. Call the guys about the KBC before you buy.
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Mooseyard said:
I'm referring to the motor speed. The VFD has the ability to double the motors rated speed, so if you get a 1750 RPM motor, you can actually get 3500 RPM out of it. My understanding is that by doing it this way you have increased torque through the lower RPMs.

I have a Leeson 2hp 1750 RPM motor on my grinder with a KBAC 27 VFD (essentially the same set-up you are looking at, but I have less HP). I rarely run the grinder at over 50%. Perhaps it's just because I'm new and I find I have better control at slower speeds. Maybe when I get more experience I will find more of a reason for the higher RPM's.

I hope this helps.
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Thank you all for bearing with me and explaining it all! My current config is setup for direct drive. I'd have to get some pillow blocks and pulleys to convert it. I'd rather keep it direct drive. Thanks all! I think I have a better understanding now. I'll go with the 1750 rpm motor. They are the same motor, but they are configured differently and there are trade offs with the higher RPMS.. I didn't know that. Great explanations and info!
 
otpowell said:
Thank you all for bearing with me and explaining it all! My current config is setup for direct drive. I'd have to get some pillow blocks and pulleys to convert it. I'd rather keep it direct drive. Thanks all! I think I have a better understanding now. I'll go with the 1750 rpm motor. They are the same motor, but they are configured differently and there are trade offs with the higher RPMS.. I didn't know that. Great explanations and info!
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Good choice. If you notice the drop off in torque when using the 2x jumper while grinding near full rpm, you can then convert to intermediate pulley system.
 
PT Doc said:
Good choice. If you notice the drop off in torque when using the 2x jumper while grinding near full rpm, you can then convert to intermediate pulley system.
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How does a intermediate pully system enable you to maintain torque while keeping the same rpm? Something has to give right?
 
otpowell said:
How does a intermediate pully system enable you to maintain torque while keeping the same rpm? Something has to give right?
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You would NOT use the 2x jumper with a pulley setup. By picking the correct pulley sizes you can create whatever SFPM belt speed you want. This gets you 100% torque at max rpm @ 60 hz AND the end belt speed you want. Another variable that can enter this picture of motor and belt speed is the size of the drive wheel. A 4" drive does not change the sfpm much at all (5%) compared the the rpm value but a 6" drive will has a 57% increase in sfpm compared to rpm.

For example, if you used a pulley ratio to achieve 4000 rpm at the drive shaft then a 4" drive will would get a belt speed of 4186 sfpm. A 6" drive wheel with this setup would result in 6280 sfpm. There is a losses of torque with a larger drive wheel, but with a 3 hp motor, I don't think you would have an issue.

I created a very detailed right up on this a while back with specific pulley sizes. If you dig around, you should be able to find it if you want more detail.
 
Would this be a good option for a motor if I am not able to set up a VFD at this time?

http://www.ptjindustrial.com/Leeson_Electric_110089_p/110089.htm or

or

http://www.ptjindustrial.com/Leeson_Electric_113938_p/113938.htm

Looks like the only difference is shaft size?

I assume that a single phase motor would not be usable/upgradeable to utilize a VFD in the future? If so I would be stuck with step pulleys for this set up (which other than the inconvenience of having to stop to change speeds seems to work just fine for achieving various desirable belt speeds).

Sorry for the semi hijack this thread has answered a lot of questions I had but am still lacking much understanding on the electric side of things. So for simplicity I'm thinking step pulleys would prob be a better bet on my first grinder.

Thanks
 
I don't think those motors are TEFC rated - for professional use a TEFC motor is a must to prevent early damage from all that steel grinding dust. For the record, I'm using basically the same motor off an old air compressor, 2 hp, 3450 rpm, running on 240vac 1 ph. Since the motor was free from the junk pile, I'll run it as long as it lasts, then look for a TEFC motor. For my casual use, I suspect it will last a good long while..... who knows. If it goes crash tomorrow, nothing lost.

You are correct, a 1ph motor doesn't work very well with a VFD.

Ken H>
 
The Technical Specs description is as follows:

Leeson 110089 1.5HP 1725 56H 115/230V Farm Duty Motor

HP: 1.5
RPM: 1725
Frame: 56H
Voltage:115/230
Service Factor: 1.15
Full Load Amps: 17.2/8.6
Hertz: 60
Efficiency: 79.0%
Enclosure: TEFC
Rotation: Reversible
Protection: Manual
Shaft Size: 5/8"
Weight: 40 lbs
Warranty: 18 Months

Single phase so I should be able to just wire up a switch and plug into regular residential outlet and be all set correct?
 
That is correct..... to a point. Are you planning for 110vac operation? Oopos, I see the TEFC rating now - I missed that on the webpage, and right there it is under "tech specs" tab. That will be a GREAT motor for a grinder using a 3 (or 4) stage pulley setup. Take about 10 secs to change belt speeds.

Note, at 120vac it's drawing 17 amps at full load, and starting load will exceed that a tad, and be sure to use a night heavy 12 gauge extension cord. Remember the standard residential outlet is only rated at 15 amps, and wired with #14 wire. You just might have too much voltage drop for 120 vac operation. Now, "IF" you have a separate 30 amp breaker feeding a 20 amp recept, and a fairly short #12 extension cord to motor, then the 2 hp motor will run just fine as there should be low voltage drop. MUCH better to run a 2 hp motor on 240 circuit. If you can provide 120 vac with no voltage drop, the motor won't know the difference between 120 or 240 vac and will run just fine.

Ken H>
 
HuffHK said:
The Technical Specs description is as follows:

Leeson 110089 1.5HP 1725 56H 115/230V Farm Duty Motor

HP: 1.5
RPM: 1725
Frame: 56H
Voltage:115/230
Service Factor: 1.15
Full Load Amps: 17.2/8.6
Hertz: 60
Efficiency: 79.0%
Enclosure: TEFC
Rotation: Reversible
Protection: Manual
Shaft Size: 5/8"
Weight: 40 lbs
Warranty: 18 Months

Single phase so I should be able to just wire up a switch and plug into regular residential outlet and be all set correct?
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No


Unless you have twenty amp breakers and outlets

the seventeen refers to amps at one hundred and ten volts, the eight point six at two hundered and twenty volts


You will have to go down to a one horsepower motor for plug and play in a "regular residential outlet"

Edited to add" Ken beat me to it.
 
Dan,

While I'm sure this post was well intended, it's not going to help people.

Yes, we can probably all agree that Baldor makes better motors than Leeson. However, the price differences we've been finding lately aren't marginal. PTJ industrial has a number of good quality inverter rated Leeson motors in the 1.5-3hp range many hundreds of dollars less expensive than their Baldor equivalents. With free very fast shipping. A 3hp 3-ph 56C (which most grinders require) motor is running like $250 shipped. If you can find a new non-old-stock Baldor inverter ready motor for near that price, I'd be interested in hearing about it. Hell last I looked, Baldor only offered one model of 56C frame 3hp 3ph motors that was compatible. Retail on it is roughly $1k. I've got one it's great, but there's no discernible difference between it and my 3hp Leeson.


I've had exactly the same number of Leeson motors and Baldor motors burn out on me that were new: Zero. I've had a number of NOS Baldor motors die on me however. Admittedly I've never owned an old stock Leeson.



As far as the drive you recommend, it's not a Nema 4x or dust proof enclosed drive. The *best* currently available reasonably priced VFDs for variable speed grinders have been for years, and still are the KB Electronics KBAC models. They're all dust proof, analogue or digital controls, handle up to 3hp on single phase and invert from 110 to 220v 3ph up to 1.5hp. The hitachi drives you linked appear to handle the same input/output requirements, but they are open enclosures, filled with sensitive electronics. That's the major concern. If someone is going to build an enclosure anyway, there are dozens of dirt cheap alternatives on ebay.
 
LEESON does not offer 3ph 3hp 56C inverter duty motor. Their 56C only goes up to 1.5hp. That's an inverter duty motor from Lincoln.

The only one from LEESON at 1.5hp is LM22663 Which is around $500 plus you have to order quantity 15 minimum.

LM22663

Baldor has couple of different choices at 3ph 1.5hp 56C. Baldor offer 56C inverter duty motors upto 2hp.

Baldor

I agree on the pricing. Baldor prices has gone up significantly. May be it's after the ABB acquisition.

The best NEMA 4X VFD that I have used is TB Wood's Etrac. It's a little more expensive than other NEMA 4X models in the market. It is now Vacon X-Series after the merger.

X-Series

I would look at AC Tech's SMVector series for a reasonably priced NEMA 4X drive.

SMVector
 
Wrong Dan, sorry. I said inverter rated, not "inverter duty" which is distinguished as something different, but not necessary for our use. Here's the motor, many of us are using, from the above mentioned source: http://www.ptjindustrial.com/Leeson_116107_p/116107.htm

It has gone up $100 recently it seems. It's still very inexpensive to any of the Baldor Vector motors. Still, $350 shipped. Although many of us paid $250.

Edit: Yes technically it's a 56HC, but that's absolutely fine for our purposes here, the primary concerns being C-face mounting, and a 5/8" shaft for mounting the available drive wheels. Nobody that I'm aware of is making 3/4 or 7/8 drive wheels atm, although I've threatened to.



Still, on the topic of VFDs, why should we be looking at AC Tech VFDs that cost more than the tried and proven KB Electronic's KBAC models, that thousands of us are using on a daily basis with nothing but great results? I've had a dozen, know people that have used many many more, and nobody has had any issues that wasn't taken care of by KB support. I had one repair, due to me doing something I shouldn't have, and they repaired it for very very little money.


You're making my point, which is; "that I don't understand yours"? Are you just trying to throw options at us? Or just trying to come around showing off your knowledge of motors and drive controllers? I'm not trying to be rude, I'm truly not sure what you're hoping to accomplish here.

Your only posts on BF since 2011 are about VFDs, so I'm guessing you either work in the motor or drive industry, and are just looking for something to talk about.. Are you a knifemaker using motors and VFDs for knifemaking applications, i.e. primarily belt and disc grinders? I'm here talking about what works great and offers great value for just that. I'm not saying I'm an expert, but me and countless of my peers have distilled the options down to the suggestions I'm touting, and in context.


I'll keep it simple, if you want a great motor and VFD combo for your belt or disc grinder, best bang for buck with longevity in a high production knife shop: Leeson 3-ph (TEFC, 56C*) motors from ptjindustrial and KB Electronics KBAC 24D, 27D, or 29, from whomever has the best price this week. Analog speed control is highly advantageous in our application.


It doesn't have to be any more complicated than that.

dan_jenson said:
LEESON does not offer 3ph 3hp 56C inverter duty motor. Their 56C only goes up to 1.5hp. That's an inverter duty motor from Lincoln.

The only one from LEESON at 1.5hp is LM22663 Which is around $500 plus you have to order quantity 15 minimum.

LM22663

Baldor has couple of different choices at 3ph 1.5hp 56C. Baldor offer 56C inverter duty motors upto 2hp.

Baldor

I agree on the pricing. Baldor prices has gone up significantly. May be it's after the ABB acquisition.

The best NEMA 4X VFD that I have used is TB Wood's Etrac. It's a little more expensive than other NEMA 4X models in the market. It is now Vacon X-Series after the merger.

X-Series

I would look at AC Tech's SMVector series for a reasonably priced NEMA 4X drive.

SMVector
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Can I use the KBAC 24D or is the 27D the one to get?I see that the 24D is about 100 dollars cheaper,I'm not sure why?
 
pbaker said:
Can I use the KBAC 24D or is the 27D the one to get?I see that the 24D is about 100 dollars cheaper,I'm not sure why?
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The difference is horsepower rating, the 24 is 1HP the 27 is 2

go with the 27, a 1.5 HP motor and you can plug it into any 110v 15 amp outlet
 
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