Abstract : In recent years, variable frequency speed control technology has developed rapidly in China, and its application fields cover various industries and civil sectors. This article introduces the application of variable frequency speed control technology in coal preparation plants, fans, and pumps, as well as its excellent speed control performance and energy-saving effect. Keywords : Variable frequency drive, fan, pump, energy saving 1. Overview The most urgent task facing China's modernization is to solve the problems of severe energy shortage and excessive raw material consumption. Comparing energy consumption per unit of GDP, China's is 4.5 times that of Japan, 5 times that of former West Germany, and 4 times that of the United States. To solve the energy problem, it is necessary to reduce energy consumption while rationally and effectively developing energy resources, thus lowering the consumption per unit of output, which is energy conservation. Fans and pumps in coal preparation plants consume a large portion of electricity, and in the past, they were driven by constant-speed motors (i.e., constant electrical power), with flow rate regulated by valves and baffles. From the characteristics of fans and pumps, it is known that flow rate is directly proportional to the speed of the driving motor, pressure is directly proportional to the square of the speed, and electrical power is directly proportional to the cube of the speed. Therefore, if the flow rate is adjusted by changing the motor speed, the energy consumption of fans and pumps will be significantly reduced, especially under low-load operation, where the energy-saving effect will be very significant. 2. Application of AC Frequency Converters In several years of production practice, we have used Meidensha VT 200S and Fuji's FRNIC C5000P 7, FRNIC5000P9, and FRNIC50001 1 frequency converters. Below, we will use Fuji's FRNIC500o series frequency converter as an example to introduce its usage: [b][align=center]For details, please click: Application of Variable Frequency Speed ​​Control Technology in Coal Preparation Plants[/align][/b]