Chinese VFD with regular 3 phases motor

[jeffrey001]

Hi, I have a spare 2.2Kw Chinese VFD and would like to control speed and direction of rotation on a standard 3 phases 1/4 HP motor.

Can this be done without problem for the VFD.

Thanks for any input.


Jeff

[Al_The_Man]

It should work OK, and trying it will certainly not harm the motor or the VFD.
Usually there are parameters that are obtained from the motor plate, plug these in if it takes the lower current rating.
Al.

[Christian Knüll]

Hello,

it should work - but bear in mind that this VFD goes up to 400Hz which is quite a bit too much for a standard motor.
If you have the same model as I have you'll need to set parameter 4 (base frequency) to 50 or 60 Hz and limit parameter 5 (maximum frequency) to someting more reasonable e.g. 100 Hz
You may also like to limit maximum current (parameters 123, 124, 125 and 142) to protect the motor.

I've used my chinese VFD to power a lathe some time ago - it worked well...

[jeffrey001]

Thanks guys, I was aware for the settings on the VFD, I already have one for a 2.2Kw spindle motor, I was not sure for the standard motor.

This is a 1/4 HP with a gear box, 3 phases geared at 33 RPM so just want to get about 25 to 50 RPM. so at 100Hz, this should work.

I also want easy forward and reverse from a single switch.

This is for a metel roller project I'm working on.

Attached a picture of the motor.

Thanks again, Jeff

[Al_The_Man]

Is it a 2 pole or 4 pole motor?
4 pole I usually take up to 120Hz, but 100hz for a 2 pole I would say is pushing the the limit at 6000rpm.
Al.

[jeffrey001]

The specs are:

50/60HZ

0.18KW

1360/1670RPM

220-266/380-460V

IP55

I think that 1670 should be 1800 because 7200/4=1800

(120 X F)/nP

So probably a 4 poles motor

I don't find any calculation for 1360 and 1670 RPM

Any tought

[UUU]

Yes, it sounds like a four-pole that you've got. I've often wondered why the speeds of these motors vary. 1425 rpm at 50 Hz is common, there must be some slippage or other effect going on. Comments from those in the know would be welcomed.

[UUU]

I've just looked up "induction motor" in Wikipedia - and yes, there's a slippage in these motors, from the fully synchronous speed.

[Al_The_Man]

I've just looked up "induction motor" in Wikipedia - and yes, there's a slippage in these motors, from the fully synchronous speed.

A normal induction motor can never reach synchronism, there will always be slip in order to keep rotating, there would be no rotor current at sychro.
The slip varies from one design to another and at off load speed is approx 3-7 cycles, typically.

Jeffrey001 you have a 4 pole motor so it is usually OK to take it up to 120hz.
Al. .

[jeffrey001]

If I remember well, slippage can vary from 3% to 10% depending on the motor construction.

Jeff