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Ppendix, Constant power calibration – Rockwell Automation SA500 Drive Configuration and Programming User Manual

Page 115

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Constant Power Calibration

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PPENDIX

E

Constant Power Calibration

Typically, an induction motor operating at or less than its rated speed will be capable of
generating its rated torque output. When a motor is operating at more than its rated
speed, its ability to generate torque decreases as the speed increases. To
compensate for this reduction of torque-producing capability, the magnetizing current
can be reduced as a function of motor speed or an external RPM signal. Reducing the
magnetizing current (Iz) enables the motor’s voltage to remain constant at speeds up
to four times base speed. This allows operation in the motor’s constant power region.
See figure E.1. The maximum speed attainable is dependent upon the motor and the
application. Motors typically can only be operated in the 1.5:1 to 2:1 speed ranges.

Constant power capability is only available for applications using induction motors with
Vector - Speed Loop Enhanced regulators. You need to select Constant Power on the
Motor Data parameter entry screen to enable constant power operation.

Figure E.1 – Typical Motor Operation in the Constant Torque and Constant Power Regions

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Constant Torque
Operating Range

Constant Power
Operating Range

Rated Motor
Voltage

Rated Motor
Torque

Motor Speed