When selecting frequency converters for speed regulation or energy saving, the following 10 principles should be followed as a prerequisite for deciding on a solution. Local electricity prices are higher, resulting in greater economic benefits for the same amount of electricity saved; this is also a factor that must be considered.
1) There are certain conditions for frequency converters to save energy. Under the condition that the use is not affected, by appropriately changing the operating parameters, the power consumed by unreasonable operating parameters can be saved, and the operation can be transformed from normal operation to economical operation.
2) To save energy, the frequency must be reduced. The greater the reduction, the more electricity is saved. In principle, without reducing the frequency, the inverter cannot save electricity.
3) It is related to the motor load rate. When the load rate is between 10% and 90%, the energy saving rate is at most about 8% to 10%, and the energy saving rate is higher when the load rate is lower. However, the reactive power saving rate is about 40% to 50%, which is not included in the electricity bill.
4) It is related to the rationality of the original operating parameters. For example, it is related to the adjustable values of pressure, flow rate, speed, etc. A larger adjustable value results in a higher energy saving rate, and vice versa.
5) This is related to the original adjustment method. Adjusting operating parameters using inlet or outlet valves is very uneconomical. Switching to frequency converter speed control is more economical and reasonable. Using frequency converter speed control can save 20% to 30% more electricity than manually adjusting the operation using valves.
6) This is related to the original speed control method. For example, the original speed control using a slip-ring motor was inefficient, especially at medium and low speeds where the efficiency was below 50%, making it very uneconomical. Switching to frequency converter speed control saved this energy. Currently, slip-ring motors are still widely used in light industry, textiles, papermaking, printing and dyeing, plastics, and rubber industries. Therefore, using frequency converters to achieve energy saving and technological transformation is an urgent task.
7) It depends on the operating mode of the motor. For example, the energy savings are different for continuous operation, short-term operation, and intermittent operation.
8) It is related to the length of time the motor is running. For example, if the motor is run for 24 hours a day or 365 days a year, the energy savings will be greater, and vice versa.
9) It is related to the power of the motor itself. Under the same energy-saving rate, the larger the power, the greater the energy saving value and the greater the economic benefits, even if the energy saving rate is relatively lower than that of a smaller power motor, the actual benefits are greater.
10) It is related to the importance of the production process equipment in this unit. First, select equipment with high power consumption, high product cost, and whose current speed regulation method is not economical and reasonable, and modify it. After replacing it with frequency converter, there will be immediate and twice the result with half the effort.
