Variable Frequency Drive (VFD) Energy Saving
The energy-saving benefits of VFDs are primarily seen in fan and pump applications. When fans and pumps utilize variable frequency speed control, the energy savings range from 20% to 60%. This is because the actual power consumption of fan and pump loads is essentially proportional to the cube of the speed. When the user requires a lower average flow rate, using variable frequency speed control to reduce the speed of the fans and pumps results in significant energy savings. Traditional fans and pumps use baffles and valves for flow control, with the motor speed remaining essentially constant, resulting in little change in power consumption. Statistics show that fans and pumps account for 31% of national electricity consumption and 50% of industrial electricity consumption. Therefore, using variable frequency speed control devices on these types of loads is of great importance. Currently, successful applications include constant pressure water supply, various types of fans, central air conditioning, and hydraulic pumps with variable frequency speed control.
Applications in Automation Systems
Because VFDs have built-in 32-bit or 16-bit microprocessors, they possess various arithmetic logic operations and intelligent control functions, with output frequency accuracy of 0.1% to 0.01%, and are equipped with comprehensive detection and protection mechanisms. Therefore, they are widely used in automation systems. Examples include winding, stretching, metering, and wire guiding in the chemical fiber industry; flat glass annealing furnaces, glass kiln stirring, edge pulling machines, and bottle making machines in the glass industry; automatic feeding and batching systems for electric arc furnaces; and intelligent control of elevators. VFDs are also used in CNC machine tool control, automotive production lines, papermaking, and elevators to improve process levels and product quality.
Applications in Improving Process Levels and Product Quality
VFDs can also be widely applied in various mechanical equipment control fields such as conveying, lifting, extrusion, and machine tools. They can improve process levels and product quality, reduce equipment impact and noise, and extend equipment lifespan. Using variable frequency speed control simplifies the mechanical system, making operation and control more convenient, and in some cases, even changing the original process specifications, thereby improving the overall functionality of the equipment. For example, in setting machines used in textiles and many other industries, the internal temperature is regulated by changing the amount of hot air supplied. Hot air is usually supplied by a circulating fan, and since the fan speed is constant, the amount of hot air supplied can only be adjusted by a damper. If the damper control malfunctions or is improperly adjusted, it can cause the setting machine to lose control, thus affecting the quality of the finished product. High-speed starting of the circulating fan causes significant wear between the drive belt and bearings, making the drive belt a consumable item. After adopting variable frequency speed control, temperature regulation can be achieved by automatically adjusting the fan speed through the frequency converter, solving the product quality problem. In addition, the frequency converter can easily achieve low-frequency, low-speed starting of the fan, reducing wear between the drive belt and bearings, extending the service life of the equipment, and saving 40% on energy.
Achieving soft start of the motor
Hard starting of the motor not only causes a severe impact on the power grid but also requires excessive power grid capacity. The large current and vibration generated during starting cause significant damage to baffles and valves, which is extremely detrimental to the service life of the equipment and pipelines. However, with the use of a frequency converter, the soft start function allows the starting current to vary from zero, with the maximum value not exceeding the rated current, reducing the impact on the power grid and the requirements for power supply capacity, extending the service life of the equipment and valves, and saving on equipment maintenance costs.