Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control (PanelView 550) - Manual (Page 258)

258 Rockwell Automation Publication 7000-UM151E-EN-P - January 2013
Appendix A General Reference
PowerFlex 7000 Drive
Performance (Torque
Capabilities)
The PowerFlex 7000 drives have been tested on a dynamometer to verify
performance under locked rotor, accelerating, and low speed-high torque
conditions.
Table 12 shows the PowerFlex 7000 drive torque capabilities as a
percent of motor rated torque, independent of the drive’s momentary overload
conditions.
Table 12 - PowerFlex 7000 Drive Torque Capabilities
** Drive will require over sizing to achieve greater than 100% continuous torque.
Glossary of Terms
Breakaway Torque: Torque required to start a machine from standstill.
Accelerating Torque: Torque required to accelerate a load to a given speed, in a
certain period of time. The following formula may be used to calculate the
average torque to accelerate a known inertia (WK
2):
T = (WK 2 x change in RPM) / 308t
where:
• T = acceleration torque in N.m (lb.-ft.)
• W = force N or kg f (lb.)
• K = gyration radius m (ft.)
• WK2 = total system inertia (kg f x m2 [lb.-ft.2
] ) that the motor must
accelerate, including motor, gear box, and load
• t = time (seconds) to accelerate total system load
Steady State Torque: Continuous operating torque required to control the load,
without instability.
Torque Limit: An electronic method of limiting the maximum torque available
from the motor. The software in a drive typically sets the torque limit to 150% of
motor rated torque.
Parameter 7000 Torque Capability
Without Tachometer (% of
Motor Rated Torque)
7000 Torque Capability With
Tachometer
(% of Motor Rated Torque)
Breakaway Torque 90% 150%
Accelerating Torque 90% (0-8 Hertz) 140% (0-8 Hertz)
125% (9-75 Hertz) 140% (9-75 Hertz)
Steady State Torque
125% (9-75 Hertz) **
100% (1-2 Hertz)
140% (3-60 Hertz) **
Maximum Torque Limit 150% 150%