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Sunday, April 30, 2017
The Motion Control Community Forum, sponsored by Control Technology Corporation.
Control Cards of Inverter
Does having a power factor improvement panel effect in any way the control side operation of the variable speed drive?

Does having a power factor improvement panel effect in any way the control side operation of the variable speed drive? In the power side the current is reduced and its good for the system, but does it interfere in any way with the control cards of the inverter?

Please share your experiences.

A VFD will correct the displacement power factor of the motor to .95 on it's own, so if that's the only significant load, additional PF correction will likely cause more harm than good.

PFC capacitors can resonate with the DC bus capacitors inside of the VFD and create high DC bus voltages that can be problematic in all sort of wats. If you need to have PF correction for other Across-The-Line/DOL motor loads in a facility, it's better to use what are called "at load" PFC capacitors that are only switched on when the offending motor is switched on.