VFD QUESTIONS

[sharpshooter90]

I'm back from assignment and thought I would get back to work on my VFD upgrade. Reading through my book, I find that the frequency can be set for up to 400Hz maximum. My motors are 1725 rpm 60Hz rated- which I conclude is that at 60Hz, they will be going 1725 rpm. If I were to set the Hz at 400, theoretically the motor would spin up to about 11500 rpm. Obviously, that would probably blow the bearings apart in short order. My question is if there is any other consideration beyond the physical limitations of the motor- Say if I set the max Hz to 100, then I could spin the motors up to about 2900 for special jobs. I'm mostly concerned that trying to go too far could damage the control unit itself.
Any input from the electronics types would be appreciated.

[Al_The_Man]

There have been a few previous post on this, generally for a non-vector rated motor it can be assumed that the motor manufacturer would produce 2 pole motors to similar specs as the 4 pole (1725rpm) type, so running a 4 pole motor at 120hz would produce the same rpm that you would normally obtain from the same motor if it were a 2 pole running on 60hz.
Al.

[mactec54]

sharpshooter90

You can run your motor at that 100Hz is fine, you can go to 120 Hz usually with no problems, but don't go above 120Hz, if you are running low RPM, then you may need to add a small fan on top of the motor as it will not get enough air flow over the motor when it is running slow