Customer Success Story – VFD Drive Replacement

Upgrading an obsolete 18 pulse VFD with a new Rockwell Automation Powerflex® 755TL drive.

        By Curt Plett, Director of Engineering, Systems Interface

        September, 2020

A Washington State Water District had three 250hp Robicon VFD’s that have been in place sine 2008. The drives were old enough that they were starting to fail. Spare parts were hard to come by to keep the drives in operation. The water district decided to upgrade the drives to new Rockwell Automation Powerflex® 755TL drives.

The proof is in the pudding!

The new drive is a low harmonic drive which gave the water district similar harmonic mitigation as the 18 Pulse Robicon VFD’s. The biggest challenge to the project was that the water district wanted to keep the existing enclosures and mount the new drives in them. Our Systems Interface electrician, Chris Wood, took up the challenge of figuring out how to remove the existing Robicon drive and mount the new Rockwell Automation drive.

As the pictures show, Chris did a masterful job in fitting in the new drive and making it look like it came that way from the factory. Thanks to Systems Interface’s project engineer, Michael Hudson for coordinating everything on this project and to TJ McDermott, project manager, for successfully starting up the new Powerflex 755TL drive.

The picture on the left is a legacy Robicon variable frequency drive System shown prior to the conversion. The picture on the right is the same panel after Systems Interface upgraded it to a Rockwell Automation Powerflex® 755TL drive System.

On Variable frequency drive migration projects of this nature, Systems Interface works closely with our clients to provide new VFD schematics, install the new drive parameters for the new platform, and fully test the drive system once installed.

Commissioning and Startup

Systems Interface provided a complete solution from design through installation, including training and commissioning service to upgrade their older VFD’s.

About the author: Curt Plett

Curt Plett is the Director of Engineering at Systems Interface in Mukilteo, Washington.