800W Spindle with 2.2kw VFD

[MustangviennA]

Hi guys,
i am new to the cnc world, and wanted to build a cnc control box. The only part that i still have to buy is a VFD for my 800W watercooled spindle.
Right now i have a 1500W Nowforever d100 VFD installed in the controller box that came with the cnc machine.

The only nowforever VFD i can find on ebay is a 2.2kw one. There are no 1.5kw ones.
Is it recommended to use the stronger one with the 800W Spindle?? Are there any advantages even? Maybe disadvantages`?

I have talked with the chinese seller and he is telling me that its ok, but i wanted to make sure.

I would really appreciate an answer.

Thank you

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[Jim Dawson]

The 1500W VFD you already have should work fine with the new 800W motor. Just try to set the maximum VFD output current to match the 800W motor nameplate current.

[MustangviennA]

The 1500W VFD you already have should work fine with the new 800W motor. Just try to set the maximum VFD output current to match the 800W motor nameplate current.

The thing is the cnc machine came allready with the 800W spi dle. Everything is working correctly. I just wanted to make a new controllerbox with a custom casing, new drivers and breakout board. Its an replacement, and the original one will stay for spare parts or in case something goes bad on the new one.

I have all the parts for the new controll box except the vfd. So will a 2.2kw vfd be good or should i try to buy a 1.5kw vfd somewhere else? I will stick with the 800W spindle for now, because it gets the job perfectly done.

[Jim Dawson]

If you are going to use a 800W spindle, a 2.2KW VFD will run it. But, you may not be able to adjust the minimum amps to match the 800W spindle nameplate current thus you would not have full overcurrent protection for the motor. I have used a 12KW VFD to run a 2.2KW motor with no problems.

[MustangviennA]

If you are going to use a 800W spindle, a 2.2KW VFD will run it. But, you may not be able to adjust the minimum amps to match the 800W spindle nameplate current thus you would not have full overcurrent protection for the motor. I have used a 12KW VFD to run a 2.2KW motor with no problems.

I wish i would understand what all of that means
Do i need the full overcurrent protection? Whats the spindle nameplate ?

[Jim Dawson]

Normally you don't want the motor to draw more current than it is rated for. The VFD will limit the motor current to a safe level if it is able to do so, prevents burning up the motor in case of a stall or overload.

Spindle nameplate, also called data plate or data tag = the information on the motor telling you the Voltage, KW, Amps, RPM, and other needed information.

[MustangviennA]

Normally you don't want the motor to draw more current than it is rated for. The VFD will limit the motor current to a safe level if it is able to do so, prevents burning up the motor in case of a stall or overload.

Spindle nameplate, also called data plate or data tag = the information on the motor telling you the Voltage, KW, Amps, RPM, and other needed information.

Ok thats some good info you gave me. I will then buy a 1.5kw vfd if its protecting better then the 2.2kw one.
If i have understood it right the nearer the max output number of the vfd to the max output number of the spindle, the greater is the overload protection.

I saw some 1.5kw ones on aliexpress, will probably go that route instead i think. Thanks again.

[mactec54]

The thing is the cnc machine came allready with the 800W spi dle. Everything is working correctly. I just wanted to make a new controllerbox with a custom casing, new drivers and breakout board. Its an replacement, and the original one will stay for spare parts or in case something goes bad on the new one.

I have all the parts for the new controll box except the vfd. So will a 2.2kw vfd be good or should i try to buy a 1.5kw vfd somewhere else? I will stick with the 800W spindle for now, because it gets the job perfectly done.

1.5Kw is a good size for your 800w spindle I would try and get the same size if you can, 2.2Kw is not needed, but will work just fine, if you program it correctly, even the 1.5Kw will have to be programed correctly

[Goemon]

If you are going to use a 800W spindle, a 2.2KW VFD will run it. But, you may not be able to adjust the minimum amps to match the 800W spindle nameplate current thus you would not have full overcurrent protection for the motor. I have used a 12KW VFD to run a 2.2KW motor with no problems.

My VFD has no lower limit for the max amps it can draw. You just set it to whatever it says on your spindle nameplate. Does your VFD prevent you was entering a lower value than the VFD's maximum draw?

The only limit on mine is the upper limit.

[Jim Dawson]

My VFD has no lower limit for the max amps it can draw. You just set it to whatever it says on your spindle nameplate. Does your VFD prevent you was entering a lower value than the VFD's maximum draw?

The only limit on mine is the upper limit.

I have run into some VFDs where there is a limit on the minimum current setting, not possible to set them to 1 amp for instance.

[Goemon]

I have run into some VFDs where there is a limit on the minimum current setting, not possible to set them to 1 amp for instance.

That would suck. I take a lot of comfort from the ability to set my VFD not to output more than my spindle can handle.

still, a 2.2kw VFD is not that much of a jump for an 800watt spindle. I'd be amazed (in a bad way) if it couldn't be set up with the appropriate limits for the spindle. My 7.5kw VFD can be set all the way down to .1a.

[mactec54]

My VFD has no lower limit for the max amps it can draw. You just set it to whatever it says on your spindle nameplate. Does your VFD prevent you was entering a lower value than the VFD's maximum draw?

The only limit on mine is the upper limit.

You are mistaken when you set the Spindle / Motor rated amps in the VFD that is what is in control of the max output and other parameters are set at 100% then that is all that the VF Drive will output, it does not matter what size it is if the correct Parameters are set

There is only a problem when the VFD Drive is too small for the Motor / Spindle it is running

[mactec54]

That would suck. I take a lot of comfort from the ability to set my VFD not to output more than my spindle can handle.

still, a 2.2kw VFD is not that much of a jump for an 800watt spindle. I'd be amazed (in a bad way) if it couldn't be set up with the appropriate limits for the spindle. My 7.5kw VFD can be set all the way down to .1a.

You could use your 7.5Kw VFD to drive the 800w Spindle / Motor if you wanted to, and it would be completely safe

Your VFD Drive amp minimum is only dependent on what model it is, by the spec's for the Huanyang GT they start at .8a all the way up to 6000a not .1a

[Jim Dawson]

That would suck. I take a lot of comfort from the ability to set my VFD not to output more than my spindle can handle.

still, a 2.2kw VFD is not that much of a jump for an 800watt spindle. I'd be amazed (in a bad way) if it couldn't be set up with the appropriate limits for the spindle. My 7.5kw VFD can be set all the way down to .1a.

This would only be a problem when the VFD is rated much higher than the motor. For instance, I have a 1/2 hp grinder and I grabbed a 2 HP VFD off the shelf to power it up because that's what I had. I don't remember the exact numbers but as I recall, the minimum current setting was about 30% higher than the motor rating.