Motor & VFD

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otpowell

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I'm looking for a motor around 2hp or 3hp for my 2x72 grinder and looking for a VFD. Can anyone suggest a good motor and VFD that's also a reasonable price? Been researching a few, and before I make mistakes to learn from, I'm hoping to learn from yours and buy the right stuff the first time around. The power I have available is a 250V Nema 6-50 and I can also wire a new receptacle if needed. Want something with plenty of power for a 2x72 grinder.
 
That's the right VFD for sure Stan, but I wouldn't consider that motor suitable.

It's a drip proof non sealed enclosure, without a C-face, which may or may not matter depending on his grinder, but generally a 56 frame C face motor in TEFC or TENV is preferable.

That's the best deal I'm aware of on the KBAC VFDs, which are the best IMHO for grinder applications, here's a good deal on a 2hp, Leeson, 56 frame C face motor, that's inverter rated: http://www.ptjindustrial.com/Leeson_116106_p/116106.htm


They offer free, very fast shipping.


Bear in mind that if you want 2hp output with single phase input you'll have to use a 220V line into the VFD with the KBAC 27D, if you want to run a 3hp motor, you'll need to order the KBAC 29 1p, and it will only accept 220V input.

If you want to run 110V input your max output is 1.5hp, but you're fine using a 2hp motor in that configuration with the KBAC 27D.
 
Your right on the motor I put TEFC in my search didn't look close enough at what came up:eek:

Stan
 
javand said:
That's the right VFD for sure Stan, but I wouldn't consider that motor suitable.

It's a drip proof non sealed enclosure, without a C-face, which may or may not matter depending on his grinder, but generally a 56 frame C face motor in TEFC or TENV is preferable.

That's the best deal I'm aware of on the KBAC VFDs, which are the best IMHO for grinder applications, here's a good deal on a 2hp, Leeson, 56 frame C face motor, that's inverter rated: http://www.ptjindustrial.com/Leeson_116106_p/116106.htm


They offer free, very fast shipping.


Bear in mind that if you want 2hp output with single phase input you'll have to use a 220V line into the VFD with the KBAC 27D, if you want to run a 3hp motor, you'll need to order the KBAC 29 1p, and it will only accept 220V input.

If you want to run 110V input your max output is 1.5hp, but you're fine using a 2hp motor in that configuration with the KBAC 27D.
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1740 rpm, sounds kind of slow doesn't it? I want at least 8000scfm out of this thing. How many scfm would I get with a 5 inch drive wheel? How do you calculate the SCFM again? I'm learning more because I really don't know much about motors. So for the KBAC 29 1p, that would be one phase in and 3 phase power out to the 3phase motor, correct? I think I want a 3hp motor just to have some extra torque. Sorry for all the crazy question, still have a lot to learn! Thanks so much everyone.
 
otpowell said:
1740 rpm, sounds kind of slow doesn't it? I want at least 8000scfm out of this thing. How many scfm would I get with a 5 inch drive wheel? How do you calculate the SCFM again? I'm learning more because I really don't know much about motors. So for the KBAC 29 1p, that would be one phase in and 3 phase power out to the 3phase motor, correct? I think I want a 3hp motor just to have some extra torque. Sorry for all the crazy question, still have a lot to learn! Thanks so much everyone.
Click to expand...

A 3 hp motor requires a 3 hp controller and larger wire - breakers to feed it.
Most makers are happy with two hp, some do have three.


That vfd has a jumper option that will double the speed output.


There is some torque related.advantage to using a two pole motor vs a four


I don't understand how that works and haven't tried it in person.



(drive wheel diameter x 3.14) x rpm
gives you inches per minute

divide that by 12 to get sfpm





I think that 8000 fpm is pretty fast.

What speed do the abrasive manufacturers recommend?
 
A VFD can usually run a 4-pole motor (1800 RPM or thereabouts on the plate) up to around 3000-3600 RPM.

Below the rated speed, it runs in "constant torque". The voltage increases with the frequency and the power (torque x RPM) goes up with it. Once the voltage reaches the rated voltage, it stops increasing (the motor can't take any more voltage without damage), but the frequency, and therefore the speed, continues to increase. This happens with "constant power" and the torque reduces as the speed increases.

If you compare a 2HP 2-pole motor and a 2HP4-pole motor, both running from 0-3600 RPM;

at 900 RPM, the 2-pole produces 1/2 HP, whereas the 4-pole produces 1 HP.

At 1800 RPM, the 2-pole produces 1 HP, whereas the 4-pole produces 2 HP.

At 2700 RPM, the 2-pole produces 1 1/2 HP, whereas the 4-pole produces 2 HP.

At 3600 RPM, the 2-pole produces 2HP and the 4-pole produces 2HP.

Because of the economics of manufacture, the 2-pole and 4-pole variants of a given frame size will usually share the same rotating components, so the motor will almost certainly have been designed for operation at 3600 RPM. The windings determine the speed and these are static. It is therefore better to use a 4-pole motor with a VFD than a 2-pole, because it is ahead on power all the way up to 3600 RPM.
 
A 3hp motor will require a different slightly more expensive VFD (KBAC 29 (1P)), which will *only* accept 220V input. You'll need a 20 amp dual pole breaker to run it. If you're planning to do extensive shop wiring anyway, or can DIY, then that's not a big hurdle.

If you plan to start running from a 110v single phase input, you need the KBAC 27D, which will run up to 1.5hp with 110v single phase input, or 2hp with a 220v single phase input.


I can point you in the direction of a 3hp motor.

I have two 3hp grinders and 1 2hp grinder. The only time the 3hp is apparently more powerful is in extreme flat platen hogging pressure, which you're not likely to be capable of as a beginner, and most full time professional makers I know run 1.5hp or 2hp and are plenty pleased with it.

Jimmy Crowell on the other hand kept locking up the 2hp variable Bader BIII's and Haywood, he'd over heat one, move to the next, at one point 3 of them were shut down from overheating. So if you're like Crowell, get the 3hp, otherwise, don't over think things. You can always upgrade later with minimal loss if you buy the right components, they're resell-able for very little loss, or what's more likely, you'll add another more powerful grinder to the mix.

I've got 3 2x72's, and wouldn't have my feelings hurt to have 2 or 3 more. You can survive with one, but having two or more is much more useful than having one "ultimate" grinder.
 
I'm not that thrilled with one thing about the VFD setup on my disk grinder- turning the RPMs down means you turn down the torque, too.
Based on that, I'm putting pulleys on the 1.5 hp 2x72 I'm building.

Any thoughts from more experienced makers on this?
Perhaps if you're not hogging hard, you don't need the torque...
 
javand said:
A 3hp motor will require a different slightly more expensive VFD (KBAC 29 (1P)), which will *only* accept 220V input. You'll need a 20 amp dual pole breaker to run it. If you're planning to do extensive shop wiring anyway, or can DIY, then that's not a big hurdle.

If you plan to start running from a 110v single phase input, you need the KBAC 27D, which will run up to 1.5hp with 110v single phase input, or 2hp with a 220v single phase input.


I can point you in the direction of a 3hp motor.

I have two 3hp grinders and 1 2hp grinder. The only time the 3hp is apparently more powerful is in extreme flat platen hogging pressure, which you're not likely to be capable of as a beginner, and most full time professional makers I know run 1.5hp or 2hp and are plenty pleased with it.

Jimmy Crowell on the other hand kept locking up the 2hp variable Bader BIII's and Haywood, he'd over heat one, move to the next, at one point 3 of them were shut down from overheating. So if you're like Crowell, get the 3hp, otherwise, don't over think things. You can always upgrade later with minimal loss if you buy the right components, they're resell-able for very little loss, or what's more likely, you'll add another more powerful grinder to the mix.

I've got 3 2x72's, and wouldn't have my feelings hurt to have 2 or 3 more. You can survive with one, but having two or more is much more useful than having one "ultimate" grinder.
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Hi thanks for all the wonderful info guys! I already have a 250v outlet with a 50aml breaker. Whatever this 3hp motor needs I can wire a new receptacle if I can't use my existing one for my welder. I'm researching and learning more about VFDS and electric motors. Interesting stuff. Been running my 2x72 off of a treadmill motor and man it's just becoming too much work to keep the variable speed maintained. They way it's step, I have to run a pretty lengthy shaft so that the controller can measure its speed. I'm looking to move my belt grinder to a mobile steel base and clean it up nice with a good motor and a vfd. If you can view the pic you'll see what I mean. Same grinder but I do have new wheels now though. Lots of trial and error and now I think I'm running pretty good.


 
Ok guys, here's what I'm planning to buy. I want to verify that I picked the right stuff. Thanks so much everyone!




3 Horsepower 3450 RPM 208-230/460 Volt 56HC Frame Three Phase Totally Enclosed Fan Cooled Induction Electric Motor
http://www.ptjindustrial.com/Leeson_114615_p/114615.htm


KBAC-29 3HP NEMA 4X VFD 230VAC 1PH INPUT 10001
http://www.electricmotorwholesale.com/10001-KBAC-29D/


Do I need any wiring to wire the two together? What kind of receptacles does the motor and VFD have? Do you have to plug both of them in or just the VFD?
 
otpowell said:
Ok guys, here's what I'm planning to buy. I want to verify that I picked the right stuff. Thanks so much everyone!




3 Horsepower 3450 RPM 208-230/460 Volt 56HC Frame Three Phase Totally Enclosed Fan Cooled Induction Electric Motor
http://www.ptjindustrial.com/Leeson_114615_p/114615.htm


KBAC-29 3HP NEMA 4X VFD 230VAC 1PH INPUT 10001
http://www.electricmotorwholesale.com/10001-KBAC-29D/


Do I need any wiring to wire the two together? What kind of receptacles does the motor and VFD have? Do you have to plug both of them in or just the VFD?
Click to expand...

Looks good

get the manual from the KB electronics website
You can just wire the vfd to the motor, or you can put plugs in if you want
four blade twist lock is what I used


See the Beaumont metal website he has good instructions there


http://www.bladeforums.com/forums/showthread.php/937348-KBAC-27D-options?p=10698180#post10698180
 
I think you want the 1750 motor not the 3450. If I understand the 1750 is a 4-pole and the 3450 is 2 pole.
 
Mooseyard said:
I think you want the 1750 motor not the 3450. If I understand the 1750 is a 4-pole and the 3450 is 2 pole.
Click to expand...

I have no idea what the means. Is this related to the phase input? Thanks for the info all I still have plenty of reading to do.
 
Read post #8 again.it explains the reason. You can set your VFD to double the speed of the motor and have better torque.

Stan
 
otpowell said:
I have no idea what the means. Is this related to the phase input? Thanks for the info all I still have plenty of reading to do.
Click to expand...

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.
 
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.
 
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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