2x72 grinder build/3 phase or single using a vfd

[israel kirby]

hello all, im building a second 2x72 using a reeder chassis,i have heard of guys using a 3phase ac motor,and a vfd drive so with that said what are your ideas on this,im looking at 2hp ac option for this I do not have 3 phase power to my garage,so im assuming the conversion would come from the motor to vfd and then to the 220 outlet? I do have in the garage.any help would be greatly appreciated my current 2x72 is pully based and ac motor single phase,also if that is the case what suggestions do you have on vfd choices ?

 

[kuraki]

That's what most of us do. Because there are 1000 combinations of motors and VFDs that will work, from used to cheap new to expensive new, and it's been rehashed many times, I won't make any suggestions on particular products.

But yes, you will run 220v 1ph from your panel, to the VFD. The VFD will run 220 3ph to the motor. You'll either buy a VFD with, or want to install your own potentiometer to control the speed by varying the frequency of the VFD from 0 to 120 hz. You can run a 1750 RPM motor at double speed. A 1750 RPM motor with a 4" or 5" belt drive wheel gives you a pretty standard configuration for speeds.

Just make sure the VFD is rated for single phase in, three phase out, and minimum rated for the same HP as the motor you use.

 

[israel kirby]

Thank you i will get to work......

 

[NJBillK]

I thought the highest HP rated motor that can be ran off of a 1p.h. line (with a VFD acting as a phase converter) was a 1.5hp 3p.h. motor.

This is why folks run a VFD on a single phase line, otherwise they are relegated to a motor that is 1hp or lower.

Please double check this prior to plunking down cash for a motor.

 

[JTknives]

I thought the highest HP rated motor that can be ran off of a 1p.h. line (with a VFD acting as a phase converter) was a 1.5hp 3p.h. motor.

This is why folks run a VFD on a single phase line, otherwise they are relegated to a motor that is 1hp or lower.

Please double check this prior to plunking down cash for a motor.

It's all about amps, you can run a 10hp single phase off a 220v 50a breaker. A 110v 20a outlet is limited to the motor it will power but not so with 220v

 

[Geoff Flato]

One thing I figure worth mentioning is not to turn the speed all the way up on the VFD without checking it's maximum HZ output. The Hitachi I recently installed on the surface grinder will go all the way to 400hz, and I imagine a 60hz motor might not appreciate being over driven quite that much

 

[JTknives]

No there is a limit to how much you can over drive it. There is a name for it where the stator starts slipping. Meaning it actually gets slower and has zero power. On my grinder it was when I tryied to go over 120hz.

 

[Lieblad]

Be sure its bearings & lube can take the extra heat. Perhaps insulation too.

But does not seem a big problem with these small grinders most guys are using.
At least seems I never hear about it.

 

[Britt_Askew]

I thought the highest HP rated motor that can be ran off of a 1p.h. line (with a VFD acting as a phase converter) was a 1.5hp 3p.h. motor.

This is why folks run a VFD on a single phase line, otherwise they are relegated to a motor that is 1hp or lower.

Please double check this prior to plunking down cash for a motor.

They make different size vfd's ,they make a vfd for 2hp and a vfd for 3hp motors among others. The reason folks use a vfd is to have variable speed.

 

[12345678910]

hello all, im building a second 2x72 using a reeder chassis,i have heard of guys using a 3phase ac motor,and a vfd drive so with that said what are your ideas on this,im looking at 2hp ac option for this I do not have 3 phase power to my garage,so

im assuming the conversion would come from the motor to vfd and then to the 220 outlet?

I do have in the garage.any help would be greatly appreciated my current 2x72 is pully based and ac motor single phase,also if that is the case what suggestions do you have on vfd choices ?

Backwards.
Power will go from the 220 outlet, through the VFD and to the motor

I thought the highest HP rated motor that can be ran off of a 1p.h. line (with a VFD acting as a phase converter) was a 1.5hp 3p.h. motor.

Not quite right

If you use a KBAC-27D, you can get 1.5 hp from a 120 VAC outlet

If you want 2 HP, you must use 220VAC input, however that's still single phase.

 

[NJBillK]

Not quite right

If you use a KBAC-27D, you can get 1.5 hp from a 120 VAC outlet

If you want 2 HP, you must use 220VAC input, however that's still single phase.

That's exactly the setup I was referring to.
- 1.5hp 3p.h. motor on a 1p.h. line through a VFD acting as a phase converter.

But I have since learned that you can actually run a high h.p. motor since it comes down to the amperage. See post #5 for further information.

 

[NJBillK]

They make different size vfd's ,they make a vfd for 2hp and a vfd for 3hp motors among others. The reason folks use a vfd is to have variable speed.

I understand what the purpose of a VFD is (variable speed), but one of the draws to a VFD on a single phase line, is that you can run a three phase motor, though I was under the impression that the H.P. cap was 1.5hp.

Now due to JTknives information in post #5, I am doing further research.

 

[kuraki]

No one would want to run 3 phase motors if there was a way to get variable speed as easily and inexpensively with a 1 phase motor. It's the only "draw" to using a VFD.

You still ignore the voltage, and can't have a full understanding of what JT explained without taking voltage into context. Amps x Volts = Power (in watts)

For all practical purposes:
To use 120v single phase input to a VFD and 3 phase motor: 1.5hp is the limit due to 120v lines being limited to 20 amps and loss in the conversion. This still requires a 240v motor. The VFD changes the 120v single phase input to 240v 3 phase output.

To use 120v single phase without a VFD to power a single phase motor, since there is no loss in conversion, you can run a 2hp motor.

Using 240v single phase input to a VFD and a 3 phase motor allows you to use as large of a motor you can find suitable components for, provided you have the power service to run it, because 240v circuits are not limited to 20 amps, and the increased potential of higher voltage allows for lower amperage draw for the same net power.

 

[12345678910]

It's all about amps, you can run a 10hp single phase off a 220v 50a breaker.

A 110v 20a outlet is limited to the motor it will power but not so with 220v

I understand what the purpose of a VFD is (variable speed), but one of the draws to a VFD on a single phase line, is that you can run a three phase motor, though I was under the impression that the H.P. cap was 1.5hp.

Now due to JTknives information in post #5, I am doing further research.

Read the manuals for the vfd you want
read them 10 times over if you need to.

The HP cap of 1.5 hp for a 120 vac circuit is imposed by the VFD, specifically a KBAC-27D drive

If you want 2 Hp, you need a 220vac input
My standard reply has a nice little summary of variable speed.


Yes you can go to vfd's and bigger motors off of 220 single phase, but when you go bigger some vfd's are 3 phase input at 240vac or 440vac.
And prices go up up up

 

[NJBillK]

Yes you can go to vfd's and bigger motors off of 220 single phase

This is where my lack of knowledge was leading to misunderstanding.

I was not aware of single phase having a capability of higher voltage. I was under the (uninformed) impression that single phase was limiter to 120 and under, and three phase was needed for a 208 vac line or higher.

So even though I was saying a 1.5hp 3p.h. motor can be ran off of a 120vac line, it is limited by the amperage of the line and the VFD (KBAC-27D in this case) is essentially giving the motor the capability of being ran off of a single phase 120vac line, not the maximum available H.P. since there are high H.P. single phase lines and motors?
Otherwise the the 1.5hp 3p.h. motor would not work on the 120vac line due to the phase incompatibility (say with a KBAC-24D), correct?