Rockwell Automation Publication 6000-TD004D-EN-P - November 2017 27
Functional Descriptions Chapter 1
When these three functions are all enabled, the behavior is shown in following
diagram.
Figure 10 - Voltage Dip Withstand Capability
Voltage Sag
This function is used to make sure that the PowerFlex 6000 drive is able to work
well when the input voltage drops to less than 30% of the required voltage. It
includes the following sub-functions: voltage loop, flux regulation, and derating.
The voltage loop function uses the PI control method and is able to keep the
output voltage equal with the given voltage dynamically if the input voltage sag is
minor. If the input voltage sag is major, the PI controller will enter saturation
mode, and the output frequency will drop down to a new, ideal value determined
by the V/F controller. Also, the output frequency will continue to drop to a new,
ideal value. This is to avoid overheating of the input transformer.
To enable this function, set Voltage Loop Enable (P290) to “1”. If Flux Control
Regulation Control Enable (P273) is set to “1”, the output frequency will drop
while the output voltage is kept at a constant value. This is to optimize the flux
when the output voltage is smaller than the given voltage. If Flux Control
Regulation Control Enable is set to “0”, the output frequency will be kept at the
given value, while the output voltage is kept at a constant value. The motor will
work in the “weak magnetic” mode during this time.
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