Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - Classic Control - Manual (Page 235)

4-76 Commissioning
7000-UM150I-EN-P – June 2013 7000 “B” Frame
3. Stator Resistance
Parameter “R stator ” is used in the hardware reconstruction of the
rotor flux. If this parameter is not adjusted correctly, the resulting
distortion in the flux feedback may cause speed feedback or motor
synchronization errors. Stator resistance must be tuned during
commissioning because it is affected not only by motor parameters,
but also by cable length. Stator resistance can be measured with the
motor stationary. The following Autotune procedure can be used
A T T E N T I O N A T T E N T I O N In the following steps, the rotation of the motor
in an undesirable direction may occur. To guard
against possible equipment damage, it is
recommended that the motor is disconnected
from the load and tested for direction prior to
proceeding, should the equipment be sensitive to
reverse direction rotation.
1. Ensure that the motor is stationary. If the motor is turning, the
results of the test may be invalid. It is not necessary to lock the
rotor.
2. Set parameter "Autotune select" in "Autotuning" to Stator Rest.
3. Start the drive. The output frequency ramps up to 2 Hz with the
motor current remaining at zero.
The motor current then jumps up to approximately 0.10 pu for less than
a second and the drive shuts off. This test produces a small amount of
motor torque and some rotation may occur.
Parameter "Autotune Rs" is set to the measured Stator resistance and
parameter "Autotune select" is set to Off. If the test is successful,
parameter "Stator resistance" in "Motor Model" is set equal to
"Autotune Rs". If the test fails, then parameter "Stator resistance" is
not changed and a warning is issued indicating the cause of the failure:
R stator hi - this is probably caused by extremely long motor
cables increasing the apparent stator resistance of the motor. The
drive cannot operate with stator resistance greater than 0.20 pu.