Rockwell Automation 1336VT AC DRIVE 5-300AMP (2-160KW) PROGRAMMING MANUAL - Manual (Page 84)

Start and Run Boost Settings
Appendix A
A-2
DC Boost
Usually increased starting torque requires more DC boost. High boost may
produce unnecessary current at low frequency and contribute to motor
overheating. Excessive boost may force the drive into MOPC resulting in
poor drive performance. The optimum DC boost is the lowest level that
will permit satisfactory starting torque in a properly sized motor and drive
application.
Start and Run Boost Settings
By using a combination of start and run boost, the following procedure
provides a selectable DC boost voltage to the motor at low drive frequency.
The correct boost combination will allow the drive and motor to adapt to
the different starting torque conditions encountered in both low and high
HP applications, while helping to prevent motor overheating.
Parameters Used
Output Current –– Parameter 2
DC Boost Select –– Parameter 9
Start Boost –– Parameter 48
Preset Frequency –– Parameters 27, 28, 29, 73, 74, 75 or 76
Run Boost –– Parameter 83
Procedure
The following setup procedure is performed with the motor connected to
the load. To optimize starting torque and help prevent motor overheating,
perform all seven steps. Steps 1-3 are performed at low frequency settings
(below 10 Hz) –– Steps 4-7 at the highest operating frequency (typically
60 Hz).
1. Set DC boost (Parameter 9) to its factory setting of 2, then set the local
speed pot or one of the preset frequencies to a value below 10 Hz.
Start the drive.
The motor should accelerate to the value set.
2. If the motor does not accelerate smoothly, DC boost must be added to
the motor. Gradually increase DC boost (Parameter 9) from 2 to 10 until
set speed is reached.