Which Spindle and VFD... again

[adam_m]

This 4.5Kw spindle is 16.5 amps.

65% more power.

https://www.ebay.com/itm/CNC-Spindle...r=501966307089

Triple the price though...

So I should be looking for something drawing more like 15 amp for a 4kw unit?

[mactec54]

I can't believe that a 4Kw motor would only draw 10A at 220V!!!

It can't, do the math that would be when it is run on 380v the other thing it may tell you is that it is not a 4Kw spindle but only 2.2Kw

[ericks]

It can't, do the math that would be when it is run on 380v the other thing it may tell you is that it is not a 4Kw spindle but only 2.2Kw

I know...that's why i said i don't believe it. My little Sako VFD is supposedly rated for 2.2 Kw, somehow i doubt that too

[ericks]

Triple the price though...

So I should be looking for something drawing more like 15 amp for a 4kw unit?

What's the reason why you wanting such a high Kw spindle?

[adam_m]

I was just trying to maximize the investment since the difference in the price seems to be about $100...

From the feedback it looks like a 10amp spindle is not realistic for a 4.5kw unit.

I believe I've also seen a 3.5kw or 3kw unit drawing about 15amps which I think is a bit more realistic...?

[ericks]

I was just trying to maximize the investment since the difference in the price seems to be about $100...

From the feedback it looks like a 10amp spindle is not realistic for a 4.5kw unit.

I believe I've also seen a 3.5kw or 3kw unit drawing about 15amps which I think is a bit more realistic...?

No 10 A is not realistic my Hertz 2.0 KW spindle's FLA is 9.0

[mactec54]

I was just trying to maximize the investment since the difference in the price seems to be about $100...

From the feedback it looks like a 10amp spindle is not realistic for a 4.5kw unit.

I believe I've also seen a 3.5kw or 3kw unit drawing about 15amps which I think is a bit more realistic...?

Yes that is close to what it should be 3.5Kw would be around 16 amps so 15 amps would be ok if that is what they had listed, just remember this will draw at the VFD input up to double the amps that the spindle will use when using single phase input power supply

I just think there labeling is incorrect you see this a lot on all the Chinese Drives and Spindles

[adam_m]

Still trying to understand the amp to kw and labeling on these motors.

I ran a cross a calculator on the internet and I think they are using the current from the VFD @ 3phase to calculate amps, unless I'm totally off base, totally possible and out of my league here.

Anyway here is what I came up with using a .9 factor a 1 factor gets even closer to the "As advertised" ratings.

4KW motor:
https://www.amazon.com/Bearing-Engra...QAPGKE8T9FERBV

https://www.amazon.com/Mophorn-Spind...9P81HPTC6NTZNP


2.2KW motor:
https://www.amazon.com/Air-cooled-24...9P81HPTC6NTZNP

So does this mean they are using 3 phase for the calculation of the motor amperage?

Am I totally off base here...

[mactec54]

Still trying to understand the amp to kw and labeling on these motors.

I ran a cross a calculator on the internet and I think they are using the current from the VFD @ 3phase to calculate amps, unless I'm totally off base, totally possible and out of my league here.

Anyway here is what I came up with using a .9 factor a 1 factor gets even closer to the "As advertised" ratings.

So does this mean they are using 3 phase for the calculation of the motor amperage?

Am I totally off base here...

The Power factor is the applied power

The power factor is the ratio of real power used to do work to the apparent power supplied to the system or circuit. Power factors receive values between 0 and 1. When no real power is present, the power factor is 0. When all power is real and none is reactive, the power factor is 1. If a utility company’s power factor is less than 1, it must supply more current to the system or user to optimize output. A large power factor is desired, while a low power factor is the result of inefficient electrical power measurements.

Real or working power refers to the work-producing power used to run the system or equipment. Real power is the power utilized in electric heating, lighting and electric appliances. Real power is measured in kilowatts. Reactive power refers to the non-working producing power needed to magnetize and start the equipment. It is a type of inductive load and measured in kilovolt-amperes-reactive units. Apparent power is the product of amperes and volts of a circuit. Apparent power is measured in kilovolt-amperes and includes both working and reactive power measurements.

Yes they are using 3ph for the calculation of the motors, try using single phase which you will be using here is a chart for single ph up to 2.2Kw

[ericks]

I hope you will be able to decide on what to buy It's not easy as i found myself!

[adam_m]

The Power factor is the applied power

The power factor is the ratio of real power used to do work to the apparent power supplied to the system or circuit. Power factors receive values between 0 and 1. When no real power is present, the power factor is 0. When all power is real and none is reactive, the power factor is 1. If a utility company’s power factor is less than 1, it must supply more current to the system or user to optimize output. A large power factor is desired, while a low power factor is the result of inefficient electrical power measurements.

Real or working power refers to the work-producing power used to run the system or equipment. Real power is the power utilized in electric heating, lighting and electric appliances. Real power is measured in kilowatts. Reactive power refers to the non-working producing power needed to magnetize and start the equipment. It is a type of inductive load and measured in kilovolt-amperes-reactive units. Apparent power is the product of amperes and volts of a circuit. Apparent power is measured in kilovolt-amperes and includes both working and reactive power measurements.

Yes they are using 3ph for the calculation of the motors, try using single phase which you will be using here is a chart for single ph up to 2.2Kw

Thanks Mactec for the reply. Some of that is above my pay grade, lol!

I think I read/understand what you're saying that they are using the 3ph to calculate their numbers.

If that is the case, then a 3kw motor as posted above from Amazon at 10amp would be a legitimate representation of the motor assuming .9 factor.

If the calculator is correct and assuming 3ph then the motor using a .9 factor at 10amp would be calculated at 3.74KW.

https://www.rapidtables.com/calc/ele...alculator.html

try using single phase which you will be using

I thought that this will be 3ph since it will be after the VFD?

Does it not work like that... 240v in 3ph out?


[EDIT] just did a little more reading on single/3pahse and this will be a single phase install which means the spindle will need to be near 15amp to be a 3kw spindle.

[mactec54]

Thanks Mactec for the reply. Some of that is above my pay grade, lol!

I think I read/understand what you're saying that they are using the 3ph to calculate their numbers.

If that is the case, then a 3kw motor as posted above from Amazon at 10amp would be a legitimate representation of the motor assuming .9 factor.

If the calculator is correct and assuming 3ph then the motor using a .9 factor at 10amp would be calculated at 3.74KW.

https://www.rapidtables.com/calc/ele...alculator.html



I thought that this will be 3ph since it will be after the VFD?

Does it not work like that... 240v in 3ph out?


[EDIT] just did a little more reading on single/3pahse and this will be a single phase install which means the spindle will need to be near 15amp to be a 3kw spindle.

You only use a power factor for calculating the Power supply you motor does not use the same calculation just 3000 divided 220=13.6 this will give you roughly the amps the motor will require to be 3Kw =13.6 A

[skrubol]

The motor is 3 phase, so it's power should be calculated that way, but small induction motors have low power factors. Like .75. And usually around 85% efficiency. So while 10A at 240V 3 phase is 4.15 kW apparent power, for .75 pf and 85% efficiency, you're down to 2.65 kW. The drives don't put out quite 240V either. So there's no way a real 4kW spindle will draw 10A on 240V.
Input to the VFD is a different question.

[mactec54]

The motor is 3 phase, so it's power should be calculated that way, but small induction motors have low power factors. Like .75. And usually around 85% efficiency. So while 10A at 240V 3 phase is 4.15 kW apparent power, for .75 pf and 85% efficiency, you're down to 2.65 kW. The drives don't put out quite 240V either. So there's no way a real 4kW spindle will draw 10A on 240V.
Input to the VFD is a different question.

The VFD Drive will only out put what the motor voltage is set too in the VFD Drive, motor voltage Parameters which for these spindle motors most are 220v so all or any calculations can only be done using 220v

If you have ever used a real 4Kw spindle you would see that it can draw up to 18A

[adam_m]

I'm getting a little confused and my head is starting to spin as I try to take all of this in...

I have 220v single phase 40 amp service to my shop (checked the breaker).

Just confirming that I would be calculating the motor on 3phase since it will be powered by the VFD that outputs to 3phase, correct?

I was looking at this VFD, thoughts?
https://www.amazon.com/Variable-Freq...A3A1CXRHIIBHYY

I think I've landed on this spindle?
http://huajiang.cn/content/?45.html


Adam,

[ger21]

What are you calculating?

A 2.2Kw spindle should be rated at 9-10 amps.

A 4Kw spindle should be at least 15 amps. If it's less than that, it's not a 4Kw spindle.

[ericks]

Are you asking how much current you will draw from the supply thats single phase for this motor/load??

[adam_m]

What are you calculating?

A 2.2Kw spindle should be rated at 9-10 amps.

A 4Kw spindle should be at least 15 amps. If it's less than that, it's not a 4Kw spindle.

That's off of 1phase correct?

Isn't this actually 3phase since the VFD is driving the spindle which puts it closer to 4kw?

[ger21]

This is what the VFD sends to the spindle, regardless of whether you're supplying single phase or 3 phase to the VFD.

The current thatt the VFD draws may vary with single or 3 phase, but that really has nothing to do with the rating of the motor.

[ericks]

This is what the VFD sends to the spindle, regardless of whether you're supplying single phase or 3 phase to the VFD.

The current thatt the VFD draws may vary with single or 3 phase, but that really has nothing to do with the rating of the motor.

Actually this is not what the vsd sends to the spindle