Medium voltage Variable Frequency Drives ( VFD ) are commonplace in pipeline applications. Many of these have been in uninterrupted service for years, but there are times when preventive or predictive maintenance is a good idea on pipeline VFDs.
Medium voltage Drives used in pipeline applications are reliable. In fact, very reliable. It’s possible to run for years without a single instance of pipeline downtime due to the VFD.
Deciding to do routine preventive or predictive maintenance on pipeline VFDs is often difficult because it does involve downtime.
Here are a few considerations:
Per the IEEE, the average failure rate is 3 times higher for electrical systems that are NOT subject to a regular PM program. Does that mean your medium voltage pipeline VFDs are likely to fail soon? Possibly not, but it does mean your odds are higher sans a PM program.
Again per IEEE, here’s a list of likely failure causes by percentage:
- Loose Connections – 30.3%
- Moisture – 17.4%
- Line Disturbance – 10.4%
- Defective Insulation – 9.9%
- Lightening – 8.1%
- Foreign Objects – 7.3%
- Collision – 3.9%
- Overloading – 2.4%
- Dust, dirt, oil – 2.2%
- Other – 8.1%
This is a generic listing, not specifically for pipeline VFDs, but all electrical equipment.
The Toshiba Corporation did a study specifically on VFD failure causes, and this does apply directly to medium voltage pipeline VFDs. The times given are the average life time before failure on these specific components. It does not mean that yours is about to fail because its beyond these times, but it is something you should be aware of.
- Electrolytic Capacitors – 5 Years (if interested, we have a specific blog on cap failures.. see HERE)
- Cooling Fans – 3 Years
- Contact Relays – 500K operations
- Connectors – 100K operations
Our field experience reiterates this study. The most drastic failures we’ve seen are caused by bus capacitor failures. The image on the right was taken by one of our service engineers. We have many such images. Bus Cap failures, are the most common cause we see of catastrophic pipeline VFD failures.
Cooling fan failures and connector failures can also cause shut down, but rarely cause extensive VFD damage. The analogy I use most often is a timing belt in an automobile.
The manufacturers will say that you should change your timing belt at specified intervals. If you go past that interval, you MIGHT get away with it, but you’re living dangerously. IF the timing belt goes while at speed, you’re likely to destroy your engine.
It’s the same with the electrolytic bus caps in a medium voltage pipeline VFD,
So if you’re operating VFDs on your pipeline, at least consider beginning a preventive predictive maintenance program. You can call us for assistance if you like. Just use any of the contact methods on the right of this page (including the on line support) or call 800-848-2504800-848-2504. You can read more about what we do during PMs HERE.
By the way.. we also sell new and refurbished medium voltage VFDs.
No One, Anywhere, is Better at Drives than we are.