Rockwell Automation FlexPak 3000 Drive Field Current Regulator Kit, 911FK0041, 911FK0101, 911FK015 - Manual (Page 35)

Modifying the Drive Configuration 5-5
5.3 Tuning the Field Current Regulator
Important: Please review Appendix A for a complete description of the functions of
the field current regulator prior to proceeding with manual tuning.
In order to provide proper and responsive field current control the user may be
required to modify the tuning parameters to meet the needs of the application.
Adjustment of the field regulator tuning may be required to properly clamp and
regulate the armature voltage at or above base speed motor operation.
Typically the regulator parameter settings should be adjusted so that the armature
terminal transient voltage does not exceed 115% of the rated terminal volts when the
motor is operated at or above base speed. Operation above base speed requires the
use of an extended speed range rated motor.
Typical maximum armature transient voltage levels:
• 575 VDC for 500 VDC rated motor
• 275 VDC for 240 VDC rated motor.
Over voltage of the armature could result from:
• Speed overshoot above base speed of the motor during acceleration
• Acceleration into the extended speed range operation of the motor.
Note that steady state operating armature voltage levels should be rated voltage.
5.3.1 Verifying Proper Field Regulator Tuning
During initial setup of the drive and motor, the commissioning engineer should verify
that the armature voltage is properly clamped during acceleration to motor base
speed and beyond. The motor armature voltage should be monitored during
acceleration. If the motor voltage exceeds the recommended levels during operation,
the field regulator tuning may need to be adjusted.
Tuning Techniques:
The field current regulator can be tuned using the following PC-based software:
• The PC scope function of CS3000 or WebPak CS
• The OIM can provide a step field current reference to the field economy setpoint.
This parameter can be accessed via the OIM Field Current Regulator menu
structure.
• Observe the actual field current response on the PC scope.
• If the response is over-damped (ie. slow reaction) then increase the field PI
proportional gain, P514 and/or field PI Lead Freq. P515 until proper response is
achieved.
• If the response is under-damped (ie. overshoots setpoint ) then decrease the field PI
proportional gain, P514 and/or field PI Lead Freq. P515 until proper response is
achieved.