Abstract : Injection molding machines are one of the main energy-consuming equipment in plastic product factories, and saving energy has become one of the effective ways for the injection molding industry to reduce costs and improve product competitiveness. Therefore, this paper discusses the energy-saving principle of variable frequency speed control energy-saving device, the selection of frequency converter, and the energy-saving transformation principle of injection molding machine. Keywords : chemical machinery; AC speed regulation; application research; frequency converter; variable frequency speed control energy-saving device; injection molding machine; current/voltage transmitter 1 Energy-saving principle of variable frequency speed control device Variable frequency speed regulation is the fastest developing motor speed regulation method in modern electrical engineering. Its speed equation is n=60f(1-s)/P. Where: f is the power supply frequency; P is the number of motor pole pairs; s is the motor slip rate; n is the motor speed. As long as the pump is changed, n can be changed to achieve stepless speed regulation. (1) Variable frequency energy saving. According to fluid mechanics, P (power) = Q (flow rate) × H (pressure). If the efficiency of the oil pump is constant, when the required flow rate Q is reduced, the speed n can be reduced proportionally. (2) Dynamic power factor compensation for energy saving. The cosine of a conventional quantitative pump injection molding machine is only between 0.6 and 0.8, while the variable frequency speed control device uses a filter capacitor to make cosine 1, thereby reducing reactive power loss and increasing the active power of the power grid. (3) Soft start energy saving. Using a variable frequency energy-saving device, the soft start function of the frequency converter will start the starting current from zero, and the maximum value will not exceed the rated current, reducing the impact on the power grid and the requirements for power supply capacity, and extending the service life of equipment and molds. [b][align=center]For more details, please click: Application of Variable Frequency Speed ​​Control Energy-Saving Device in Injection Molding Machines[/align][/b]