Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE - Manual (Page 237)

COMMISSIONING 9-37
1557-UM050F-EN-P – June 2013
If the flux regulator Autotuning is successful, then parameter "L magnetizing" in "P Motor Model" is set equal to
"Autotune Lm", parameter "T rotor" in "P Motor Model" is set equal to "Autotune T rotor", and parameter “Lmd” in
“P Motor Model” is set equal to “Autotune Lmd”. If the flux regulator autotuning fails then parameters "L
magnetizing", “Lmd”, and "T rotor" are not changed and a warning is issued indicating the cause of the failure.
L magn low - indicates that the measured value of magnetizing inductance is less then 1.0 pu. This warning is
intended to draw attention to an unusually low value of magnetizing inductance. The most likely cause is incorrect
scaling of the analog field current reference.
L magn high - indicates that the measured value of magnetizing inductance is greater then 10.0 pu. This warning
is intended to draw attention to an unusually high value of magnetizing inductance. The most likely cause is
incorrect scaling of the analog field current reference.
T rotor low - indicates that the calculated value of rotor time constant is less than 0.1 seconds
T rotor high - indicates that the calculated value of rotor time constant is greater than 5.0 seconds.
7. Speed Regulator
The tuning of the speed regulator is determined by two parameters in the "P Speed Control" group:
1. Spdreg bandwidth
2. Total inertia
Parameter "Spdreg bandwidth" is set to a value determined by the requirements of the application, but parameter
"Total inertia" is usually unknown and must be measured.
Speed Regulator Autotuning
The Autotuning determines the total inertia by measuring the change in speed that occurs when a low frequency
sinusoidal torque perturbation is applied to the motor. This method of measuring inertia was introduced in
firmware Rev 4.72/5.20. Previous revisions of firmware used a different method. The inertia measurement is not
affected by the load torque as long as the drive does not hit torque limit. Do not disconnect the driven load from
the motor, as it is the total inertia of motor and load that is being measured. The following procedure should be
used:
1.
Ensure that parameters "Autotune spd cmd” and "Autotune trq stp" in “P Autotune” are set to suitable
values.
2.
Set parameter "Autotune select" in “P Autotune” to 7.
3.
Start the drive. The motor accelerates normally up to the speed specified by parameter "Autotune spd
cmd". When the motor speed has settled at the commanded value, a sinusoidal perturbation specified by
parameter "Autotune trq stp" is added 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 inertia" is set to the measured inertia and parameter "Autotune select" is set to zero. If the
test is successful, parameter "Total inertia" in "P Speed Control" is set equal to "Autotune inertia" and the speed
regulator gains are recalculated. If the test fails then parameter "Total inertia" is not changed and a warning is
issued indicating the cause of the failure: