0 Introduction AC variable frequency speed control technology is a new type of electric drive speed control technology that developed rapidly in the 1980s. Variable frequency drives (hereinafter referred to as VFDs) have advantages such as a wide speed range, rigid mechanical characteristics, high precision, and reliable operation when used for speed control of AC asynchronous motors. Therefore, their application in the cement industry is becoming increasingly widespread, especially in the speed control, energy-saving operation, and soft starting of fans and pumps. Guangdong Nanhua Cement Co., Ltd. (hereinafter referred to as our company) introduced VFD technology in 1992 and has successively carried out a series of technical transformations on equipment such as air classifiers, disc feeders, and fans, achieving significant economic and social benefits. Based on our company's experience in using and maintaining VFDs over the past few years, we would like to share some experiences on how to effectively use VFDs. 1 Operating Environment Each VFD has its required operating environment. It can only work reliably under the specified environment. Therefore, if the environmental conditions are not met, corresponding measures should be taken to strive to make the entire operating environment meet the installation requirements of the VFD. For example, the Fuji FRENIC 5000G7/P7 series frequency converters used in the kiln tail exhaust fans and cooling fan motors of our clinker plant have the following environmental requirements: ① Ambient temperature -10～50°C; ② Relative humidity 20%-90%, with no condensation or freezing due to sudden temperature changes; ③ No direct sunlight, no corrosive gases, flammable gases, or water vapor; ④ Low dust and oily dust content in the air; ⑤ Altitude below 1000m; ⑤ Vibration less than 0.5g. When using this frequency converter, we compared each requirement and took a series of measures to ensure the environmental conditions met its requirements. For example, our plant has a high dust content and high ambient temperature; we increased air conditioning and implemented a "dust-blowing" measure to meet the frequency converter's requirements, ensuring reliability and extending its service life. 2. Capacity Selection Since the switching devices of the frequency converter are high-power transistors, their overcurrent capacity is smaller than that of thyristors. Therefore, the correct selection of its capacity is directly related to its operational safety. [b][align=center]For details, please click: Experience in the Application of Frequency Converters in the Cement Industry[/align][/b]