The Benefits of Variable Frequency Drives (VFDs)
VFDs help adjust motor speeds to match loads and improve efficiency while conserving energy. The benefits of VFDs are widely documented and may include:
- Ability to compensate for changing irrigation demands (flow and pressure), which may reduce energy consumption
- Reduced maintenance costs
- Increased productivity and improved crop quality
How VFDs Work
A VFD controls the rotational speed of an electric motor by controlling the frequency of the electrical power supplied to the motor. They are proven to substantially reduce energy use. Non-VFD motor-driven systems are often designed to handle peak loads and the VFD can slow down the motor to better match the part load requirements. Also, they can reduce the impact of starting the motor.
Controlling motors with a VFD offers energy savings when motor-driven processes and power demand vary over time. Energy savings from VFDs can be significant, although the amount of energy reduction will vary depending on the motor's operation and energy use. On a turbine pump, even a small reduction in motor speed can reduce a pump's energy use by as much as 30 percent. Payback can range from few months to less than 10 years. VFDs also allow more control of processes such as water distribution, aeration, and chemical feed. The variable frequency lessens mechanical and electrical stress on motors, can reduce maintenance and repair costs, and extend motor life.