For boiler fans, the relationship between flow rate Q, wind pressure H, shaft power P and speed n is: QWn, HWn2, PWn3. Therefore, when the speed is reduced to reduce the flow rate, the shaft power will be much lower. It can be seen that three methods can be used to change the speed of the asynchronous motor: 1) change the magnetic pole pair P of the stator winding of the motor, which is the variable pole speed regulation, such as the two-speed motor; 2) changing the slip rate S of the motor, which is cascade speed regulation; 3) Change the power supply frequency of the motor, which is the frequency conversion speed regulation. The frequency conversion speed regulation is applicable to many electric motors, and has the advantages of high reliability, high efficiency, good maintenance, convenient maintenance, convenient transformation, easy operation, low price, strong environmental adaptability and the like. Precautions when purchasing UPS power: (1) From the viewpoint of realizing a reliable switching operation, we hope that the phase difference of the phase difference between the bypass power source and the inverter power source is as small as possible when the UPS power source is purchased. In addition, in order to use the UPS power supply, we also need to pay full attention to the frequency stability of the power grid. The genlock control circuit of the general online UPS power supply can perform effective frequency in the commercial power frequency range of 50Hz+1%. Tracking, but for UPS operating in a grid with large frequency fluctuations, you should purchase a variety of UPS power supplies with a wide frequency tracking range. (2) Whether the bypass power supply phase-locked synchronous control loop has a strong phase-locked synchronous capture capability of the input voltage, which is mainly manifested in: the UPS power supply should be within the range of wide variation of the bypass power input voltage, bypass sine wave The power supply can synchronously control the sine wave power output of the inverter. (3) Adopt intelligent UPS power supply system. To overcome the UPS power supply system with its load. The computer and its network are independent of each other and cannot communicate with each other. In recent years, an intelligent UPS power supply system has been developed, and only the appropriate UPS monitoring card and dedicated UPS monitoring software are configured to pass through the UPS host. The monitoring communication port is connected with the computer network to form an intelligent power supply system. Freezer,Deep Freezer With Drawers,Super Cold Freezer,Small Medical Refrigerators Hellowave Technology Limited , https://www.hellowavetech.com