Rockwell Automation 20B PowerFlex 70, PowerFlex 700 Reference Manual - Manual (Page 100)

Efficiency
100 Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
Efficiency
The following chart shows typical efficiency for PWM variable frequency drives,
regardless of size. Drives are most efficient at full load and full speed.
Fan Curve
When torque performance (see page 201 ) is set to Fan/Pump, the relationship
between frequency and voltage is shown in the following figure. The fan/pump
curve generates voltage that is a function of the stator frequency squared up to the
motor nameplate frequency. Above base frequency voltage is a linear function of
frequency. At low speed the fan curve can be offset by the run boost parameter to
provide extra starting torque if needed. No extra parameters are needed for fan/
pump curve.
The pattern matches the speed vs. load characteristics of a centrifugal fan or
pump and optimizes the drive output to those characteristics.
Fan
See Fan Curve above.
10 20 30 40 50 60 70 80 90 100
% Speed/% Load
% Efficiency
vs. Speed
vs. Load
75
80
85
90
95
100
Maximum Voltage
Maximum
Frequency
Base Voltage
(Nameplate)
Base Frequency
(Nameplate)
Run Boost