Industrial Motors

How to build a reliable VFD system in 10 steps

Are you asking the right questions about your variable-frequency drives?

By Jim Montague

Implementing variable-frequency drives (VFDs) can pay back big benefits, and adopting them is easier than it might seem at first. You just have to follow a few basic guidelines, which are highlighted in "Building a Reliable VFD System" by Brian Shuman, Belden's senior product development engineer.

  1. What are the torque demands of the loads or processes in your planned system? Will any of the loads be hard to start? VFDs have limited over-current capacity, so hard-to-start loads may require an over-sized unit to cover higher current demands.
  2. How many motors will the drive control? If it's more than one, will they start sequentially or simultaneously? Calculate the total peak currents of all motor loads under the worst operating conditions your planned system will see. Size the VFD according to this maximum current requirement.

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