VFD Repair

VFD (Variable Frequency Drives) have decreased in price in recent years, and with standard VFDs, it’s often more advantageous from an economic viewpoint to replace rather than repair the VFD. At EMA, as with most reputable VFD Repair companies, we let customers know at once if in our opinion, this is the case. The customer can then make the decision to either repair the VFD, or purchase a new VFD.

All that being said, EMA still repairs VFDs, in fact we repair a significant number of VFDs. There are many reasons why a repair is preferable to replacement. (you might want to check out our main blog page.. there are several blogs about specific vfd and dc drive repairs)

• It’s a specialized VFD. We have customers with machines worth millions of dollars that have small, very specialized VFDs. Due to communication bus issues, spacing issues, or other application specific reasons, it’s just not feasible to replace them. We repair these specialized VFDs, and keep the machine running.
• It’s a large HP unit. The larger the HP, the more likely it is that repairing the VFD is a better option than replacement. EMA repairs medium voltage VFD s as well, and those are most often repair candidates rather than replacement. For one thing, the installation costs alone on a large HP VFD can be significant, often exceeding the repair costs. Here at EMA, we see significant numbers of high horsepower VFD repairs.
• Servos. Servo drives are, in general, expensive. They also tend to have application specific software and communication protocols and are often great candidates for repair.
• There are large numbers of the specific VFD in the facility. Once you have spares, your maintenance personnel have experience on the units, and you have a vfd repair company like EMA for backup, it might make more sense to stay with what you have and just repair the VFD s rather than replace with new. We have many customers in this situation. They weigh the cost of the VFD repair, against the TOTAL cost of replacement, which includes things like spares, personnel training, etc.

So, what goes wrong with VFD s? In general, VFDs are quite reliable. You’ll find some other posts within our blogs and newsletters that detail several repair suggestions, but here’s a list of common failures.

• Loose connections. Don’t laugh, it’s a major cause of VFD downtime. Check simple stuff first. Is a plug on the main circuit board loose? Try that first, before trying a more complex VFD repair.
• Cooling Fans. A major cause of problems. Some VFD s will let you know about this, but most won’t until you begin tripping on over temperature. The over heating can and almost certainly will cause major issues long term, so check this often.
• Electrolytic Capacitors. These have relatively short lives compared to other components, and, overheating shortens it even more.
• Power Semiconductors. These are less common, but drastic failures. If this happens, do NOT just replace the IGBT or Diode, find out why if failed. Or, you’ll likely just be replacing it again as soon as you power up.
• VFD Software or programming. Was it running before you tried changing a parameter? Then put it all back to where it was and see if that fixes it. Don’t automatically install factory suggested software revisions until you back up what’s running. In general, if its running fine now, leave the programming alone.
• Circuit boards. These are much less common failures than one might think, but is often the first thing suspected when an inexperienced technician begins to repair a VFD.

We give firm VFD repair quotes at EMA, and provide free evaluations in our shop. EMA also stocks and sells new world class VFDs, and can do turnkey installations. So, if you have a VFD you’d like to check on repairing, just send it to one of the locations listed at the bottom of this page, or call us at 800-848-2504 or email us by clicking at the top right of this page.

IF it’s during regular working hours.. hit the “Live Support” button to chat with a technician.. If it’ s after hours.. it will allow you to leave a message.

Visit our FIELD SERVICE and SHOP REPAIR pages

Trey Mayfield, EMA Inc.