Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 222)

4-68 Commissioning
7000A-RM001A-EN-P – January 2011 7000 “A” Frame
4. After completing the flux regulator tuning, the drive waits for a few
seconds and adds a sinusoidal perturbation specified by parameter
Autotune Trq Stp to the torque command, causing the speed to
vary. After the initial transient has decayed (this usually takes a
few seconds), the variation in torque and speed are measured and
used to calculate the Total Inertia. The torque perturbation is then
removed and the drive performs a normal stop.
Parameter Autotune L Magn (221) is set to the measured magnetizing
inductance. Parameter FlxCmd RatedLoad in Flux Control Group is set
to a value which is intended to produce rated voltage at rated speed and
load. The value of parameter Autotune T Rotor is calculated from
parameters Lm Rated and Rated Motor RPM (which gives the rated
slip).If the auto-tuning is successful, then parameter Lm Rated (131) in
Motor Model is set equal to Autotune L Magn, parameter T Rotor
(P132) in Motor Model is set equal to Autotune T Rotor, and the flux
regulator gains are recalculated, parameter Total Inertia (82) in Speed
Control is set equal to Autotune Inertia and the regulator gains are
calculated.
If the auto-tuning fails then a warning is issued indicating the cause of
the failure. Following are the list of possible warnings:
L Magnetize Low - indicates that the measured value of
magnetizing inductance is less than 1.0 pu. This warning is
intended to draw attention to an unusually low value of
magnetizing inductance. This may occur if the motor is much
larger than the drive and the nameplate parameters do not
correspond to the actual motor ratings.
L Magnetize High - indicates that the measured value of
magnetizing inductance is greater than 10.0 pu. This warning is
intended to draw attention to an unusually high value of
magnetizing inductance. This may occur if the motor is much
smaller than the drive, and the nameplate parameters do not
correspond to the actual motor ratings. The flux regulator should
be tuned using the manual method described below.
T Rotor Low - indicates that the calculated value of rotor time
constant is less than 0.2 seconds. This is caused by a value of Lm
Rated or Rated Motor RPM which is too low.
T Rotor High - indicates that the calculated value of rotor time
constant is greater than 5.0 seconds. This is caused by a value of
Lm Rated or Rated Motor RPM which is too high.
Regulator Limit - indicates that the torque command was greater
than Trq Limit Motoring or Trq Limit Braking. The measured
inertia value is invalid. Parameter Autotune Trq Stp or parameter
Autotune Spd Cmd must be set to a lower value and the test
repeated.
Tuning Procedure (cont.)