Rockwell Automation Publication 7000-UM202H-EN-P - November 2023 17
Chapter 1 PowerFlex 7000 Drive Overview
Motor Compatibility The PowerFlex 7000 drive achieves near-sinusoidal current and voltage
waveforms to the motor, resulting in no significant additional heating or
insulation stress. Temperature rise in the motor connected to the VFD is
typically 3 °C (5.5 °F) higher compared to across-the-line operation. Voltage
waveform has dv/dt of less than 50 V/
μs. The peak voltage across the motor
insulation is the rated motor RMS voltage divided by 0.707.
Reflected wave and dv/dt issues often associated with VSI drives are a non-
issue with the drive. Figure 5
shows typical motor waveforms. The drive uses a
SHE pattern in the inverter to eliminate major order harmonics, plus a small
output capacitor (integral to the drive) to eliminate harmonics at higher
speeds.
Standard motors are compatible without de-rating, even on retrofit
applications.
Motor cable distance is virtually unlimited. Rockwell Automation has tested
this technology for controlling motors up to 15 km (9.3 mi) away from the drive.
Figure 5 - Motor Waveforms at Full Load, Full Speed
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TIME (ms)
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