Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) Commissioning - ForGe Control - Manual (Page 102)

102 Rockwell Automation Publication 7000-IN012B-EN-P - June 2014
Chapter 4 Commissioning the Drive
Set the Autotune L Magn (P#221) parameter to measure magnetizing
inductance. Set the FlxCmd RatedLoad parameter in the Flux Control Group to
a value that produces rated voltage at rated speed and load. Calculate the value of
parameter Autotune T Rotor from parameters Lm Rated and Rated Motor RPM
(which gives the rated slip).
If the auto-tuning is successful:
• the Lm Rated (P#131) in Motor Model is set equal to the Autotune L
Magn;
• the T Rotor (P#132) in Motor Model is set equal to Autotune T Rotor
and recalculate the flux regulator gains; and,
• the Total Inertia (P#82) in Speed Control is set equal to Autotune Inertia
and calculate regulator gains.
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 indicates 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 indicates 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. Tune the flux regulator 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. Set the Autotune Trq Stp or Autotune Spd Cmd parameter to a
lower value and repeat the test.
• Tuning abort - indicates that the deviation in motor speed was greater than
10 Hz. The measured inertia value is invalid. Set Autotune Trq Stp to a
lower value and repeat the test.
• Inertia high - indicates that the measured total inertia is greater than
20 seconds. This warning indicates an unusually high inertia value. For a
very high inertia load such as a large fan, this may be a valid result; set Total
Inertia manually to equal Autotune Inertia. However, a high inertia
measurement might also indicates that the Autotune Trq Stp value is too
low.