Q: Why does my motor need a Variable Frequency Drive (VFD)?
A: Sometimes motors don’t need a VFD. But 95% of the time, motors are running in situations where you can/should vary the speed. You may already be varying the speed of your process via chokes or valves. Putting a VFD on a motor will extend the life of the motor and save on energy costs.
Q: How does a VFD extend the life of my motor?
A: Well, it’s all physics mainly. Heats kills electronics, and as well as mechanical devices. If you are running your motor full-out, 100%, all the time, then you are inevitably adding unnecessary heat to your system and motor. Just remember that for every 10 degrees the temperature inside of your motor rises above rated spec, you reduce the life of your motor by half! At 20 degrees, you have reduced the life by 75%!
Q: How does a VFD save energy costs?
A: Well it all goes back to the relationship of hp/kw being proportional to the speed cubed. So if we are running something at 100%, we are using the full amount of hp and kw. However, if we reduce it to say 50%, we are now only using 12.5% of the hp and kw. Put two of the 50% systems together and now you have 100% of the load you were looking for at 25% of the energy usage.
Q: How much energy are we talking? Motors don’t use that much energy, right?
A: Wrong, did you know that at very low, conservative numbers, that electric motors consume approximately 25% of the Earth’s energy consumption? At high estimates, it is as much as almost 48%. Electric motors are the single largest user of electricity in the world, so just think what that translates to your facility.
Q: Yeah but the Return on Investment is years right?
A: Not necessarily. On the medium voltage side, some of the ROIs can approach 2 to 3 years; however, on the low voltage side, ROIs can be as little as 2 months. Innovative-IDM can even help you with an energy audit of your facility to help fully develop a VFD ROI proposal.
Brandt King is a longtime member of the Innovative-IDM team at the Houston branch. You can reach him at email@example.com