Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 230)

4-76 Commissioning
7000A-RM001A-EN-P – January 2011 7000 “A” Frame
Running the Load Motor Starting Torque
When starting without a tachometer or encoder, the drive operates in
an open loop mode below approx. 3 Hz at which point the drive
switches to closed loop speed control. The starting currents are set
by three parameters; Torque Commands 0 sensorless (P86), 1 (P87),
Torque Command 0 sensorless sets the breakaway torque and Torque
Command 1 sensorless is the torque at the transition point from open
to closed loop. Torque Command Minimum operates in conjunction
with Torque Command 1 to minimize speed overshoot at the
transition point. If you are starting an uncoupled motor, or simply
auto-tuning, the default starting torque values may be sufficient to
run the motor. But the defaults are generally not high enough to start
a loaded motor.
Be prepared to have to increase starting torque and ensure Motor
Stall faults during initial operation.
Reaching Specific Load Points
Verify the drive can reach rated speed and load. Monitor the Torque
Reference (P291) and the displayed value of the motor current. If
you are running into a torque limit the Torque Reference will be
running near the Torque Limit Motoring (P84) limit. If you are not
realizing rated motor current you may increase the Torque Limit
Motoring slightly. If increasing the Torque Limit Motoring does not
help to increase the motor amps and speed then the drive is most
likely running out of input voltage.
Monitor the Line Voltage pu (P135), and increase the tap setting on
the drive feed if the measured value is less than 1.03 pu. It is
desirable to have Line Voltage pu read in the 1.03 to 1.07 pu range.
Alpha Rectifier (P327) should be greater than 15
° while running at
rated speed and load, indicating how far forward the rectifier is
phased. The input voltage should be increased by tapping up the
transformer.
Fill in the following table with data from the various load points. If
possible, capture the running parameters with the printer,
DriveTools, or Hyperterminal as a substitute for recording the data in
the table below. This should be forwarded with all commissioning
data back to Product Support for future reference.