What is Variable Frequency Drive Technology?

Posted on Wednesday, August 13, 2014 by Kimberly Versaw

Variable Frequency Drive (VFD) technology, otherwise known as an “inverter” or “AC Drive”- is a motor starting device that allows the speed of an AC motor to be varied as well as the standard “start-stop” functions.  Put simply, a VFD converts electrical energy into mechanical energy in a cost-effective and controlled manner.  Without VFD technology, the power is not converted in a clean fashion.  Before we get into more detail, some applications that require VFD technology include:  pumps, fans, lathes, mixers, conveyers, general automation, and anything where the speed of the motor needs to be controlled, but the position or accuracy of the motor is unimportant.

So why VFD technology?

With a “dirty” power source, drive systems can experience some inefficiencies and VFD technology can help alleviate issues such as:

  • Voltage irregularities (ripple effect)
  • Transient noise
  • Reflective wave (motor rejecting signal back to drive)
  • Harmonic power distortions (multiple waves, too much voltage)
  • Inrush currents (initial overload of voltage on the motor)
  • Excessive heat
  • Dielectric stress (too much going on creating stress on insulation, creating heat)
  • Potential corona

As a result of the aforementioned conditions, VFD systems are seeing issues such as bearing failure, motor failure, drive component burnout, cable breakdown, unwanted fault conditions, and unplanned system downtime. 

The next entry will discuss why we use VFD systems and how choosing the right VFD cable can help drive systems be more effecicient in energy conversion.


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