Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 22)

22 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 1 Drive Configuration
Below is the same plot with a reactor added in series. These waveform look like a
sine wave and that is a function of how much inductance is added. However, the
increased voltage drop must be accounted for.
Another option is to have a sine wave filter in the circuit. This lets unshielded
cable to be used without the worry of PWM generated noise being injected into
the facility. The cost of shielded cable versus a sine wave filter, Among other
factors, has to be weighed.
When using single phase operation, connect the load to the U and V phases. The
W phase is energized but is not used.
Enter your maximum current into the Motor NP Amps parameter. Also use this
value in the Current Limit parameter. When started the drive attempts to ramp
to the commanded voltage. If current limit is hit, the drive levels off or reduce the
voltage to satisfy the current limit.
Notice the DC Bus voltage ripple in two of the plots above. If this ripple is high
enough in magnitude, it can cause the drive to trip on an Input Phase Loss fault.
This is due to the drive monitoring the bus ripple and if a certain delta between
max volts and min volts exists for a certain amount of time, the drive assumes an
input phase was lost. This fault can be disabled by setting P462 [InPhase
LossActn] to option 0 “Ignore.”
Three Phase Output
If you are driving as resistive load, configure it in a three phase arrangement to
avoid using the single phase mode of adjustable voltage. Use a sine wave filter to
keep PWM off the resistors. If the resistors are of the ceramic type, it is possible to
crack the resistor using PWM.
Single Phase - PWM into Resistor - No Reactor
Voltage
DC Bus
Current