Rockwell Automation 7000A PowerFlex Medium Voltage Drive (A-Frame) - Classic Control - Manual (Page 251)

Commissioning 4-77
7000 “A” Frame 7000A-UM150F-EN-P – June 2013
4. Leakage Inductance
Parameter “L total leakage” 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. Leakage inductance must be tuned
during commissioning because it is affected not only by motor
parameters, but also by cable length. Leakage inductance can be
measured with the motor being 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 Leakage Ind.
3. Start the drive. The output frequency ramps up to rated frequency
in 2-3 seconds with the motor current remaining at zero. The
motor current then jumps up to approximately rated current 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 Ls" is set to the measured leakage inductance,
and parameter "Autotune select" is set to Off. If the test is successful,
parameter "L total leakage" in "Motor Model" is set equal to "Autotune
Ls". If the test fails, then parameter "L total leakage" is not changed
and a warning is issued indicating the cause of the failure:
L leakage lo - indicates that the measured leakage inductance is
less than 0.15 pu. Possible causes are:
1. The motor is much larger than the drive and the motor
nameplate parameters do not correspond to the actual motor
ratings. In this case, the measured leakage inductance is
probably correct and parameter "L total leakage" should
manually be set equal to "Autotune Ls".