Rockwell Automation 20B PowerFlex 70, PowerFlex 700 Reference Manual - Manual (Page 124)

Output Frequency
124 Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
resulting from high dv/dt. When using motor line reactors, it is recommended
that the drive PWM frequency be set to its lowest value to minimize losses in the
reactors.
By using an output reactor the effective motor voltage will be lower because of the
voltage drop across the reactor - this may also mean a reduction of motor torque.
Output Frequency
[Output Frequency]
This parameter displays the actual output frequency of the drive. The output
frequency is created by a summation of commanded frequency and any active
speed regulator such as slip compensation, PI Loop, bus regulator. The actual
output may be different than the commanded frequency.
Output Power
This parameter displays the output kW of the drive. The output power is a
calculated value and tends to be inaccurate at lower speeds. It is not
recommended for use as a process variable to control a process.
Output Voltage
[Output Voltage]
This parameter displays the actual output voltage at the drive output terminals.
The actual output voltage may be different than that determined by the sensorless
vector or V/Hz algorithms because it may be modified by features such as the
Auto-Economizer.
Overspeed Limit
The Overspeed Limit is a user programmable value that allows operation at
maximum speed but also provides an “overspeed band” that will allow a speed
regulator such as encoder feedback or slip compensation to increase the output
frequency above maximum Speed in order to maintain maximum Motor Speed.
Figure 28 illustrates a typical Custom V/Hz profile. Minimum Speed determines
the lower speed reference limit during normal operation. Maximum Speed
determines the upper speed reference limit. The two “Speed” parameters only
limit the speed reference and not the output frequency.
The actual output at maximum speed reference is the sum of the speed reference
plus “speed adder” components from functions such as slip compensation,
encoder feedback or process trim.
The Overspeed Limit is added to Maximum Speed and the sum of the two
(Speed Limit) limits is output. This sum (Speed Limit) is compared to Maximum
Frequency and an alarm is initiated which prevents operation if the Speed Limit
exceeds Maximum Frequency.