# VFD Faults on Stationary Generator and not on portable Generator



## Loose Wires (Jul 15, 2020)

Hello All

Just joined this wonderful website and was looking for some answers to my crazy,weird problem we are having with our Fuji VFD. Original MCC VFD failed and was replaced with a Fuji AS300 P11 480V 50HP. Installed it, ran it, everything worked fine. Then one day, utility power shut off power due to PSPS (Edison Public Safety Power Shutoffs due to fires). Emergency Stationary Generator kicks in and power is up and running. Submersible Pump #1 VFD trips with OV2 and also with ground fault protection. We check everything and couldn't find anything wrong. VFD does not like generator. Other original VFD which is a wattstop voltage starter, Submersible Pump #2 has no problem with generator and runs fine. Basically everything is fine as long as we have utility power running the lift station. Here is the crazy,weird problem. The lift station ATS was going to be replaced. We brought a portable generator to run the station and connected it after the ATS so the station ran on the portable generator power and Edison power/stationary generator power was lockedout/blocked out while the ATS was being replaced. When pump #1 VFD was called by PLC, the VFD ran fine. We did not expect the VFD to work because it was faulting with the stationary generator.
How do you explain the VFD not working with the stationary generator and it works with the portable generator. Any thoughts are really appreciated.
Original setup of Pump #1 VFD (TOSVERT) has Harmonics Filter on line side (before and after install of new Fuji VFD) If more additional info is needed, please feel free to ask.
Name is Al


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## Wirenuting (Sep 12, 2010)

Welcome to ET
Please take the time to fill out your profile. 

What did your electrician say?


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## micromind (Aug 11, 2007)

What is the pitch of the stationary gen?

If it's anything other than 2/3, harmonics may be the problem.


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## tmessner (Apr 1, 2013)

grounding and bonding issues.


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## gpop (May 14, 2018)

What are the voltages. After checking neutrals and grounding you can turn the voltage regulator down to 460v and see if that works.


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## JRaef (Mar 23, 2009)

Most likely, the standby generator is a higher impedance source than the utility feed, which, with the new VFD + line side harmonic filter, creates a resonance with the VFD bus capacitors that creates what's called a "DC Pump Up" phenomenon in the drive's DC bus. It happens... It may not have been an issue with the original Toshiba drive because the DC bus caps were different, and/or it had a DC bus choke, which the Fuji most likely does not have.

Try disconnecting the passive harmonic filter for now and see if the new drive runs. If it does, put a line contactor on the passive filter and set it up so that the contactor drops out when the ATS switches to the generator. You don't really need the harmonic filter when running on the generator.


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## Loose Wires (Jul 15, 2020)

micromind said:


> What is the pitch of the stationary gen?
> 
> If it's anything other than 2/3, harmonics may be the problem.


The pitch is 2/3.


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## Loose Wires (Jul 15, 2020)

gpop said:


> What are the voltages. After checking neutrals and grounding you can turn the voltage regulator down to 460v and see if that works.


The voltages coming from the generator are 480V - 478V - 479V. I will try that and lower the voltage regulator and see what we get.


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## just the cowboy (Sep 4, 2013)

As the new man here follow post #6 from @JRaef, he is the top man on VFD's

Welcome
Cowboy


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