Frequency Drive

From the attachment what would you guys /gals out there consider the nominal RPM & Frequency to be... to program in the VFD.??

I´m puzzled, lol it does not take much though
Attached Files vfd.pdf (162.6 KB, 9 views)
Last edited by porky : Today at 04:07 PM.

Why nominal?
Just plug in the min. & max per the documentation.

That is a two pole motor, and at 60 Hz the nominal speed would be 3600 rpm. The motor is designed for overspeed, since th nominal frequency range shown is 62 to 110 Hz.

In the drive's motor data section, enter 400V for motor voltage, 101.5Hz for base frequency, 79.5 for amps, and 6040rpm for base speed.

The 6040 is derived this way. Take 3600, divide it by 60 and multiply it by 110 to get the synch speed at 110Hz. This comes out to 6600rpm. The nameplate lists 6550 as the full load speed so that is 50rpm slip at full load.

Now take 3600, divide it by 60 and multiply it by 101.5 to get synch speed at 101.5hz. It works out to 6090rpm. Subtract the same 50rpm slip to get full load speed at 101.5hz.

At least with the drives I am familiar with, you need to tell the drive what the FULL LOAD speed is at the base speed so it knows what the slip is. Otherwise, if you enter the synch speed, the drive will not allow the motor to load

You might need to also set the 50% points based on 1/2 of the base freq and volts. 200 volts and 50.75 hz. This helps with acceleration and maintains the V/F ratio a bit better.

Thanks for the info... What happened when I entered the 101,5 Hz and the 6040Rpm the motor ran for max 3 seconds then the drive faulted on Overbraking.... which confused me
How ever when I entered the lower range of the motor (62 Hz and 3700 RPM) the motor ran well without problems.... I am worried that this may cause problems in the future though

Our supply Frequency is 50Hz 400Volts

DickDV....where did you get 60 and 3600 from??

porky, the 60hz and 3600rpm is the synch speed and frequency for a two pole motor. Since I knew what that was, I used a simple proportion to get to the other synchronous speeds. You could just as well used 50hz and 3000rpm if that is more familiar to you.

The problem with entering the 62hz values as you said you did is that the motor will see 400V at 62hz instead of 101.5hz. This represents significant overvoltage in the midrange of speed which I don't think is good for the motor.

If you are getting an Overbraking fault (I assume this would indicate High DC Bus Voltage due to regen energy), and it occurs while accelerating up to speed, I suspect that the drive is set up in Vector Mode and the speed loop tuning is unstable. I would change the drive to Scalar (V/Hz) mode and see if the fault problem goes away with the motor data entered correctly.

If it does, and you need the precision performance of Vector mode, switch back to Vector mode and set your P and I gains in the Speed Loop controller back down to very sluggish values.

Restart your motor, being sure that the faulting is gone, and then slowly increase the P and I gains until your speed loop is adequately tight for your application.