Upcoming Webinar:  Remote Monitoring’s Role in Reliability Centered Maintenance   Register Now →

Robicon Perfect Harmony Liquid Cooled Drives

There is consensus within the medium voltage VFD community, that liquid-cooling large medium voltage VFDs is the most efficient way of keeping them cooled while keeping the cabinet size relatively small compared to air cooled medium voltage VFDs. The downside to liquid cooling is the occasional component failures that can occur with the medium voltage VFD .

In recent weeks EMA was involved in repairing a Robicon Perfect Harmony liquid cooled medium voltage VFD that experienced catastrophic failures. (NOTE: IF you require service or assistance, call 770-448-4644) We have years of experience working on the air-cooled Robicon Perfect Harmony medium voltage drives. The Perfect Harmony VFDs have a great feature due to the inherent nature of the cascaded H-bridge topology. This topology allows bypassing failed cells (Cell-bypass option) and for having redundant cells in the Robicon Perfect Harmony VFD.

The cell bypass on the Robicon perfect harmony liquid cooled VFDs allows the VFD to bypass a bad cell and its corresponding cells in the event of cell failure. This allows the VFD to continue to run on limited capacity until such time that the customer can perform an orderly shut down. If the Robicon Perfect Harmony liquid-cooled drive has redundant cells then the VFD will bypass the bad cell and remove the bypass off one of the redundant cells.

This Robicon Perfect Harmony liquid cooled VFD had been running for three years with bad cells that were bypassed; the VFD had the redundant cell system. So even though they had bad cells within this particular liquid cooled Robicon Perfect Harmony VFD, they were able to run at full capacity. The problem was the bad cells were degrading bus capacitors that would eventually blow up since they are still receiving full voltage. That, in fact, is what happened in this Perfect Harmony VFD. The resulting arcing caused damage to the liquid piping that runs through the heat sinks of the VFD cells. As a result, glycol was sprayed all over the Robicon VFD causing extensive damage. The damage on this VFD would have been much less if this had been an air-cooled VFD.

liquid cooled RobiconThis was a critical situation, and required an all hands on deck approach. On an emergency basis, we refurbished all nine liquid cooled Robicon Perfect Harmony power cells, and got the customer back online. Our service engineers are now very familiar with both air-cooled and liquid-cooled Robicon Perfect Harmony drives. Call 800-848-2504800-848-2504 if you need assistance, or hit any of the contact methods on the right. We provide free telephone support on the Robicon Perfect Harmony VFD product.

No-One, Anywhere, is Better at Drives than we are.. no brag, just fact.. try us and find out for yourself.


Leave a Reply

Your email address will not be published. Required fields are marked *

Get the EMA blog straight to your email

Get the latest and freshest content on managing your drives.
Related Articles