VFDs: Six Benefits, Energy Efficiency
Drives: A growing emphasis on boosting energy efficiency and meeting energy requirements are increasing demand for variable frequency drives (VFDs).
The global variable frequency drive (VFD) market is slated to experience healthy growth over the coming years. These drives are emerging as an integral part of several machine markets globally both small and large scale. They are used in applications ranging from small devices to large compressors. VFDs are power conversion devices that are available as AC drives, DC drives, and Servo drives.
It is estimated electric motors in industrial applications consume approximately one fourth of the world’s electrical energy. When these motors are incorporated with VFDs in centrifugal load service, their efficiency increases. With technological advancements in power electronics technology, VFD cost and size have decreased, while performance has improved.
VFD Advantages
Globally, VFDs are used across several end-use sectors, including infrastructure, industrial, power generation, and oil and gas. Growing concerns regarding energy efficiency worldwide coupled with rising awareness about benefits of these drives are boosting their adoption across these sectors.
Six (6) primary benefits of VFDs are:
1. Keeps starting current in control. A VFD has the capability of starting the motor at zero voltage and frequency, which keeps a check on motor winding flexing and heat generation. This helps in extending the motor life.
2. Reduces power line disturbances. Any voltage sag caused in the power line can adversely affect voltage sensitive devices such as proximity switches, sensors, and computers. Using VFDs eliminates voltage sag.
3. Demands lower power on start. Power required to start on AC motor across the line is substantially greater than with a VFD. When industrial customers start these motors during peak hours of electrical consumption, they are likely to be charged with surge prices. However, with VFD demanding lower starting power, the issue can be addressed.
4. Helps in controlling operating speed and acceleration. Applications such as bottling lines that include easy to tip product significantly benefit from a gradual increase in power. This allows conveyer belts to smoothly rev up rather than an abrupt jerk to full power. They also allow speed to be remotely adjusted by a controller. Control is speed and acceleration are a big bonus to industries in a production process.
5. Limits and adjusts torque. The drive is capable of limiting and adjusting the amount of torque so the AC motor never surpasses this limit. This protects machinery from damage and protects the process or product.
6. Saves energy and cost. A VFD regulating a pump motor that usually runs less than full speed can cut down energy consumption over a motor running at constant speed for the same period. In addition, it eliminates the need for mechanical drive components, which also helps reduce overall costs.
Competition from Substitutes
Several VFD substitutes are available on the market. Soft-starter drives are one of the biggest and are useful in limiting inrush current associated with electric motor startup. They lower the initial voltage and ramp up until desired speed is attained. Soft-starter advantages include easy set-up and they’re cheaper compared to VFDs. They’re also designed to extend motor life.
VFDs do not perform as needed in no flow or near zero flow conditions and may not be well suited for specialist applications. In these cases, instantaneous high-speed response is required. These drives are acknowledged for the ability to deliver higher frequency source power during startup, which is beneficial if control is sought after the desired speed is attained.
Energy efficiency is needed to not only meet burgeoning power requirements, but curtail greenhouse emissions. On a global scale, energy efficiency can reduce greenhouse emissions by around 40%.