Hello
Alex was asking on the thread about the disk grinder about the compatibility of his motor with his VFD. There are several basic considerations.
1) The motor and the VFD should have the same voltage rating. Many 230V motors can also be configured (via connections in the termination box) to run on 480V. Make sure it is configured correctly for your application.
2) The rating of the VFD should be equal to or higher than the rating of the motor in order to get the full rated power out of your motor. The rating of the VFD should not be more than about 5 times the rating of the motor (depends on the brand and model of VFD) or the software in the VFD may have trouble controlling the motor smoothly. Some motors or VFD's are rated in kW. 1 kW = 1.34 hp.
3) It is best if the motor is rated to work with VFD's. VFD's work by approximating the 50Hz or 60Hz voltage waveform using high frequency square waves. The high frequency square waves interact with the motor and the cables going to the motor and cause very short duration voltage spikes that exceed the nominal voltage on the motor. This extra stress may cause the insulation on the motor windings to break down over time leading to a short circuit. How long a motor not rated for VFD's will work with a VFD is difficult to determine since it is a complex interaction that is dependent on some of the more subtle electrical characteristics of the VFD, the cables and the motor though it is possible to get away with it for quite a long time. Motors under 10hp are generally not worth the labor required to rebuild them so once it blows up one will have to buy another. Motors rated to work with VFD's are typically made with a higher grade of insulation than motors that are not rated to work with VFD's. One would have to refer to the motor manufacturer's literature (manual or catalogue) to determine whether or not a particular model of motor was designed to work with VFD's. I have not noticed such information on the nameplate on the motors that I have worked with.
I hope this helps.
Phil
Alex was asking on the thread about the disk grinder about the compatibility of his motor with his VFD. There are several basic considerations.
1) The motor and the VFD should have the same voltage rating. Many 230V motors can also be configured (via connections in the termination box) to run on 480V. Make sure it is configured correctly for your application.
2) The rating of the VFD should be equal to or higher than the rating of the motor in order to get the full rated power out of your motor. The rating of the VFD should not be more than about 5 times the rating of the motor (depends on the brand and model of VFD) or the software in the VFD may have trouble controlling the motor smoothly. Some motors or VFD's are rated in kW. 1 kW = 1.34 hp.
3) It is best if the motor is rated to work with VFD's. VFD's work by approximating the 50Hz or 60Hz voltage waveform using high frequency square waves. The high frequency square waves interact with the motor and the cables going to the motor and cause very short duration voltage spikes that exceed the nominal voltage on the motor. This extra stress may cause the insulation on the motor windings to break down over time leading to a short circuit. How long a motor not rated for VFD's will work with a VFD is difficult to determine since it is a complex interaction that is dependent on some of the more subtle electrical characteristics of the VFD, the cables and the motor though it is possible to get away with it for quite a long time. Motors under 10hp are generally not worth the labor required to rebuild them so once it blows up one will have to buy another. Motors rated to work with VFD's are typically made with a higher grade of insulation than motors that are not rated to work with VFD's. One would have to refer to the motor manufacturer's literature (manual or catalogue) to determine whether or not a particular model of motor was designed to work with VFD's. I have not noticed such information on the nameplate on the motors that I have worked with.
I hope this helps.
Phil