The Energy Grid

Variable Frequency Drives (VFD’s)

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VFDs save energy.

Mark Robinson

Expert technical article about how variable frequency drives save energy

Variable frequency drives (VFDs) are devices that can significantly save energy in various applications that use electric motors. In this article, we will explore how VFDs work, their benefits, and how they can save energy.

How Variable Frequency Drives Work

VFDs are electronic devices that control the speed and torque of AC electric motors. They work by converting the incoming fixed-frequency AC power to DC power and then back to AC power with variable frequency and voltage levels. By adjusting the frequency and voltage output of the VFD, the speed and torque of the motor can be precisely controlled.

Benefits of Variable Frequency Drives

The main benefits of using VFDs are energy savings, improved process control, and extended motor life.

Energy Savings: One of the primary benefits of using VFDs is energy savings. By precisely controlling the speed of the motor, VFDs can match the motor’s speed and torque to the load requirements of the application. This eliminates the energy wasted when running the motor at a constant speed even when the load requirements are low. This results in significant energy savings, which can be up to 50% or more in some cases.

Improved Process Control: VFDs can also improve process control in many applications. By controlling the motor’s speed and torque, VFDs can ensure that the process is operating at the desired speed and with the required level of precision. This can result in improved product quality, reduced scrap, and increased efficiency.

Extended Motor Life: VFDs can also extend the life of electric motors. By reducing the motor’s speed and torque when the load requirements are low, VFDs can reduce the wear and tear on the motor’s bearings, shafts, and windings. This can result in longer motor life, reduced maintenance costs, and increased reliability.

How Variable Frequency Drives Save Energy

VFDs save energy in two main ways: reducing the energy wasted when running the motor at a constant speed, and reducing the energy required to start the motor.

Reducing Energy Wasted: When a motor is running at a constant speed, it is using energy even when the load requirements are low. This energy is wasted because the motor is running faster than it needs to. By using a VFD to adjust the motor’s speed to match the load requirements, the motor only uses the energy it needs. This can result in significant energy savings.

Reducing Starting Energy: Starting a motor requires a significant amount of energy, especially for large motors. VFDs can reduce the amount of energy required to start the motor by gradually increasing the frequency and voltage levels of the AC power. This reduces the starting current and the mechanical stress on the motor’s components. By reducing the starting energy, VFDs can save energy and extend the motor’s life.

Conclusion

Variable frequency drives are powerful tools that can significantly save energy in many applications that use electric motors. By precisely controlling the speed and torque of the motor, VFDs can eliminate the energy wasted when running the motor at a constant speed and reduce the energy required to start the motor. This results in significant energy savings, improved process control, and extended motor life.

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