Variable frequency AC Drive

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Thread Starter

Bilash Khatua

I'm facing a problem when trying to operate a application that will make up and down of 3kgs weight through a motor of rating 0.75hp, 960rpm, 1.5A with a ABB355 model VFD 1hp.

The drive is unable to deliver the torque that needs to operate the process at 25RPM.

Is it the problem of the rating of VFD or Motor?

Is there any kind of load vs speed curve?

Please help me.

mail id- [email protected]
 
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Gerald Beaudoin

Trying to run a motor at <3% of the rated speed is never very good.

First of all, cooling will quickly become an issue. Most VFD's do have a parameter which enables some form of voltage-vs-hertz compensation for low-speed/high-torque starts. However, this parameter has limited effect, and is designed to mitigate a transition to running speed, not compensate for poor system design. I would seriously consider adding a reduction gearbox in order to get the motor RPM into a more reasonable range.
 
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Bob Peterson

a VFD operating in V/Hz mode at under 3% of its rated frequency is probably not going to develop much torque in the motor.

you might get a little help by setting the drive to sensorless vector mode if it has such a mode.

Another option is some kind of gear box or pulley system so the motor can run closer to its rated speed.

did you calculate how much torque you actually need and what torque the motor will be producing at 25 RPM?
 
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