440VAC, 60Hz motor on a 415VAC,50Hz supply (VFD) 3

[balaji28]

Hi - I would be running a 440VAC,60Hz,45Kw motor on a 415VAC,50Hz supply with a VFD. The motor assembly would be driving a vertical spindle assembly via a flexible coupling and worm gear (suitable for both 60Hz & 50Hz. The worm gear adapts the vertical assembly speed to the motor speed. The motor power requirement for the machine is 45Kw max. Would there any problem in operating 440VAC,60Hz,45Kw motor on a 415VAC,50Hz supply with a VFD ?

 

[edison123]

For ideal condition, you maintain the same V/Hz to preserve magnetic flux density. In your 440 V/60 Hz motor, it would be 367 V/50 Hz via your VFD.

Muthu

http://www.edison.co.in

 

[balaji28]

Hi
Thanks. Coming from non Electrical background can you please advise how does magnetic flux affect motor performance and life ? What will be impact on performance and life of this motor when operating on 415V/50Hz supply ? Please refer my application stated in my thread above

Regards
Bala

 

[edison123]

Underfluxing i.e.lower V/Hz affects starting and running torques.

Overfluxing i.e.higher V/Hz produces flux saturation, core overheat and overcurrent besides other issues.

Muthu

http://www.edison.co.in

 

[LionelHutz]

The maximum frequency you could operate the motor at while maintaining rated torque is 56.6Hz. You can't get 45kW continuously from the motor, the new rated power will be 42.4kW when operating at 56.6Hz.

Look at the very recent posts by columbo7 since most any VFD operation change question was already answered there.

 

[waross]

The magnetic flux level depends on the Volts per Hertz ratio.
For that motor the V/Hz ratio is 440V/60 Hz = 7.33
With 415 Volts supplied the proper frequency will be 415V/7.33 = 56.6 Hz.
BUT; Check the nameplate. 440 Volts has not been a standard motor frequency in North America for 50 or 60 years.
If you need more speed, connect the motor in delta for a 6 lead motor or in parallel for a 9 lead motor.
For a delta connection the voltage rating will be 254 Volts and the V/Hz ratio will be 254V / 60Hz = 4.23. The maximum frequency at 415 Volts will be 415 V / 4.23 = 98 Hz.
For a parallel connection the voltage rating will be 220 Volts and the V/Hz ratio will be 220V / 60Hz = 3.67. The maximum frequency at 415 Volts will be 113 Hz.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[balaji28]

Hi
Thanks everyone. The requirement is in India. The supply voltage is 415VAC,50Hz, whereas the motor name plate states 440VAC,60Hz,45Kw. The motor would be driving a vertical spindle assembly via a flexible coupling and worm gear (suitable for both 60Hz & 50Hz). The worm gear adapts the vertical assembly speed to the motor speed depending on the worm gear ratio & can be operated at differential speed between 60Hz & 50Hz.

An earlier supply of the similar machine had a motor with a tag plate 415VAC,50Hz,45Kw and 440VAC,60Hz,52Kw, whereas the new supply has motor tag plate only states 440VAC,60Hz,45Kw, so the customer is the opinion that the motor is not suitable for the said machine. The motor power requirement for the machine is 45Kw max.

Also another query that VFD operating on a 415VAC,50Hz supply running a 440VAC,60Hz motor will reduce the life of VFD, as VFD has to compensate for increasing from 415V,50Hz to 440V,60Hz(motor). As per my understanding Since a VFD cannot increase the voltage above its supply voltage. Please advise.

Will also check posts by columbo7

Thanks
Bala

 

[waross]

The earlier machine was rated at 52 kW at 440 Volts, 60 Hz.
The new machine is rated at 45 kW at 440 Volts, 60 Hz.
The new motor appears to be smaller than the older motor.
What is the motor driving? That may make a difference.
The new motor may not be able to handle overloads as well as the older motor.
What is the rated current of both motors?
What are the frame sizes of both motors?
We occasionally see motors manufactured outside of North America with non-standard voltage ratings, but it is good to check.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

Your new motor is smaller according to the 2 rating plates. You need to confirm the power required at the speed it will be operated and then ratio that so you can compare to the nameplate data. Using a VFD and wanting 45kW @ 40Hz is different than wanting 45kW @ 55Hz.

The VFD can't create voltage, but it's life isn't changed by the frequency it produces, so producing 415V @ 56.6Hz doesn't make a difference compared to producing 415V @ 50Hz.