VFDs: The Game Changer
Variable Frequency Drives (VFDs) are energy saving devices that came into popularity in the late 1970’s. VFDs intercept incoming electricity from the utility and modify it using Pulse Width Modulation (PWM) to meet, but not exceed, the load requirements for your specific application. VFDs are best used in applications with variable torque loads, which may not always need to run at full bore for the entirety of their lifetime. This helps you to use less energy than running a motor at full power all of the time. This also helps to reduce wear on the motor over time.
Benefits to using a VFD:
- Energy Savings
- Reduces Peak Energy Demand
- Reduces power when not required
- Fully Adjustable Speed
- Controlled starting, stopping, and acceleration
- Dynamic Torque Control
- Provides smooth motion for applications such as elevators and escalators
- Maintains speed of equipment, making drives ideal for manufacturing equipment and industrial equipment such as mixers, grinders, and crushers
- Versatility
- Self-diagnostics and communications
- Advanced overload protection
- PLC-like functionality and software programming
- Digital inputs/outputs
- Analog inputs/outputs
- Relay outputs
- Low motor starting currents
- Reduction of thermal and mechanical stresses on motors and belts during starts
- Simple installation
- High power factor
- Lower kVa
Applications that can Benefit from a VFD Include:
- Pumps
- AC Motors
- Conveyor Systems
- Elevators
- Screw Presses
- Constant Air Volume Systems
- Boilers and Forced Draught Fans
- Cooling Towers
- Drying Machines (Furnace Fans)
- Carts
- Wood Working Machines
- Weighing Machines
- Packaging Machines
- Extruders
- Cranes and Hoists
- Injection Molding Machines
- Wire Drawing Machines
- Agitators
- Rollers
- Multilevel Car Parking Towers
- Automated Warehouses
- Blowers
- HVAC Units
- Compressors
- Automation Applications Where:
- Complete speed control is required
- Energy savings is a goal
- Custom control is needed
Drawbacks to using a VFD:
- Creates Harmonics
- Requires a special wire type
- Can damage motor windings and bearings over time
- Large upfront cost
- Can reduce service factor
- Can destroy insulation over time
Using a VFD is a technical decision that needs the input of experienced technicians and industry experts who know the details of your specific application and can help you to weigh the benefits and drawbacks. The initial cost can be outweighed by the energy savings you can accrue throughout extended use of your VFD. You can find an energy savings calculator here. To help you decide if a VFD is right for your application.
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John is a marketing specialist working out of EMC’s Salt Lake City office. He oversees the articles and blog content for Energy Management Corp. On the weekends, you can catch John skiing at the resorts in Little Cottonwood Canyon.
Great delivery. Outstanding arguments. Keep up the great work.
It’s nice that you mentioned how VFDs could maintain the speed of equipment, making drives ideal for manufacturing equipment and industrial equipment such as mixers, grinders, and crushers. I was watching a video of a factory last night and I saw that they were using VFDs. According to what I’ve seen, it seems easy to buy variable frequency drives nowadays.