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EMA Inc.

The importance of routine preventative maintenance on VFDs

Variable frequency drives often fall into a “set it and forget it” mode. Modern VFDs are generally reliable so once they’re started up, they’re often given very little attention until a failure occurs, in which all hell breaks loose trying to resolve it. Routine maintenance or “preventative maintenance” is often overlooked or pushed aside by operations managers who are looking to squeeze in every last ounce of production possible. 

There is, however, significant data to justify routine, preventative maintenance on your Variable Frequency Drives. The concept of “spend a little now to save a lot later” certainly applies in this case.

IEEE performed a study in 2017 highlighting the importance of routine maintenance on power systems. They found that over 16% of failures were attributed to “inadequate maintenance” and “poor maintenance” actually contributed to more failures than no maintenance at all. 

Although this study was not aimed directly at VFDs specifically, we can reasonably assume that VFDs fall into a similar category.  

 

What is Routine?

Oftentimes the definition of “routine” varies, especially between maintenance and operations personnel. At EMA we suggest performing at least annual preventative maintenance on your medium voltage variable frequency drives; if environmental conditions are harsh, a bi-annual PM is suggested. 

Things To Check For During Preventative Maintenance

Loose connections:

Loose connections are the #1 cause of issues on variable frequency drives. Any loose connection, whether on a high-current or low-current connection is a potential point of failure. Electrical arcing happens at the loose connection which can lead to oxide build-up and extreme heat. Loose connections on low-current, control connections might not lead to heat but can cause frustrating and hard-to-find intermittent issues.

Contaminants:  

EMA Service Engineer, Brad cleans the transformer section of a Perfect Harmony Medium Voltage Drive

Oil, dirt, dust, and debris can all cause significant issues with your variable frequency drives. Heat is a major killer of any electronic component and contaminants prevent VFDs from properly dissipating the heat generated by the switching components within the drive. All VFDs have some sort of heat sink that takes heat away from the components and out into the atmosphere. If that heat sink is clogged with contaminants, it impedes its ability to do that, which can lead to premature failure.

 

Abnormal Visual and Audible Indications:

EMA Service Engineer Mike, performing preventative maintenance on a Allen Bradley Powerflex 7000

One of the best troubleshooting tools out there is the eyes and ears of highly-skilled, VFD professionals like the ones at EMA. During preventative maintenance, a skilled variable frequency drive technician should visually and audibly inspect the drive for potential signs of damage or abnormality. Components on their way to failure often show visual signs of overheating. Chattering contractors and humming transformers are just a few of the common precursors to failure that can be caught during preventative maintenance. EMA recently performed preventative maintenance on a Medium Voltage Toshiba VFD where the transformer was humming much louder than normal. Based on our recommendation the customer purchased a spare transformer and was able to get up and running much quicker when the transformer inevitably failed a few months later. 

Familiarize Yourself BEFORE You’re Forced To:

As we mentioned in a previous article, preventative maintenance is a great time to familiarize yourself with the VFD during scheduled downtime, as opposed to an unplanned, emergency situation. Preventative Maintenance is a great time to see where certain components are laid out with the VFD so when the time comes to inspect or change them, you’re already ahead of the game. Routine preventative maintenance is the perfect low-stress, hands-on training for anyone looking to gain experience with and knowledge of variable frequency drives. 

A Partner You Can Trust:

At EMA, we’ve been servicing and performing preventative maintenance on VFDs for over 30 years! We’ve got a qualified technical team traveling all over the country (and the world). Don’t leave your expensive equipment to chance! Call us at 770-448-4644, email us, or click our online chat to schedule your service today. No One ANYWHERE Is Better At Drives Than We Are!

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