Rockwell Automation 7000 PowerFlex Medium Voltage (B Frame) Commissioning - ForGe (PanelView 550) - Manual (Page 111)

Rockwell Automation Publication 7000-IN006B-EN-P - May 2013 107
Commissioning the Drive Chapter 5
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
o
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.