G120C - Actual speed rpm vs Output frequency discrepancy

Dear Sirs,

I have a G120C drive  with a 3-phase 400VAC motor (rated freq. 50Hz and rated speed 880rpm); the drive control mode is V/f linear (p1300=0).

When the speed setpoint is 880rpm (r20), the actual speed is 880rpm (r22) but the output frequency (r24) is 44Hz. Why 44Hz? I woud have expected a value of 50Hz, in agreement with the motor rated frequency.

I think this issue is linked to the slip frequency compensation, so r24 is 50-6=44Hz.

Is there a parameter that shows the drive output frequency without slip compensation included?

Actually I think that the drive output frequency should be 50Hz, and 46Hz is the motor real em field rotor frequency.

Can anyone help me?

Thanks in advance

EN

This discrepancy is due to misunderstanding of the reference speed setting.

Reference speed (P2000) should be set to the synchronous speed of the motor (in your case 1000 rpm) because output frequency = (requested speed  / 60) x pole pair number).

If you tell the drive that reference 100% is 880 you will get 44Hz at 100% (880rpm / 60 * 3 pairs of poles)

Therefore set P2000 to 1000rpm and you will get 50Hz when requesting 100% speed. 

Please check p310 and p311 

should be..

p310 =50 [Hz]

p311 =880 [rpm]