can we increase the rpm of a motor with vfd ?

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can we increase the rpm of a motor with vfd ?
I want to know that can we increase the rpm of a motor with vfd ?

lets suppose that there's a motor having rated rpm 1460 rpm at 50Hz , if we run the vfd at 60Hz or at 80Hz rather than 50Hz then by doing this , would the motor rpm be increased from 1460rpm (by increasing the frequency) ?

If it increases the rpm then would it be harmful for the motor ? And , how long would we be able to run the motor with increased rpm and frequency ?

thanks ya
 

There are two points:

- Feasible motor speed in terms of mechanical strength.
- Intended torque respectively motor torque. Usually the motor will be operated in field weakening at higher frequencies because the VFD can't further increase the motor voltage as required to keep the flux respectively torque constant. An exception is a case where the VFD can supply a higher voltage to the motor, e.g. operating a 230/400V motor in delta circuit with a 400V VFD. It can theoretically achieve full torque up to 85 Hz, if the motor can stand the speed.

Speeds of 60 or even 70 Hz can be achieved with most drives in field weakening with light load without special measures.
 


couldn't understand what you explained above ?

Might it be in a more easy and lucid manner ?

thanks
 



what do you mean by field weakening ? what is it ?
Just tell me yes or no whether rpm of a motor can be increases by a vfd ?
As i know that by increasing the output frequency of a vfd the motor operating frequency would also be increased and in response to this the rpm of motor would also be increases and there would be no harm to the motor because as rpm increases the motor cooling fan (blower fan) would also run faster to provide more cooling to the motor and the windings.
 

Just tell me yes or no whether rpm of a motor can be increases by a vfd ?
Click to expand...
The question has been already answered in post #2.
what do you mean by field weakening ? what is it ?
Click to expand...
It's a well defined technical term in power engineering. Field weaking related to VFD is briefly discussed here https://en.wikipedia.org/wiki/Variable-frequency_drive

In a short, field weakening means increasing the motor frequency without increasing the motor voltage proportionally, not keeping the V/Hz ratio.
 



I have seen the parameter in a vfd and the name of that parameter is "Field Weakening" is it the same, about which you're talking about ?

also what value should be put into this parameter of the vfd ?


It means field weakening/weaking is harmful for the motor at any speed and frequency , right ?

thanks a lot
 

It's uncommon to have a field weakening control parameter with VFD. It should be explained in the parameter manual.
 

FvM said:
It's uncommon to have a field weakening control parameter with VFD. It should be explained in the parameter manual.
Click to expand...

can field weakening be happen to any motor in any case or problem ?
 

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