Abstract : This paper introduces the usage of frequency converters at the Shanxi Branch of China Aluminum Corporation (CHALCO). Addressing common problems encountered during use, such as tripping, overvoltage display issues, and inaccurate voltage measurements, the paper focuses on methods for frequency converter fault analysis and handling. Keywords : Frequency converter; Variable frequency speed control; Inverter module; Pulse width modulation 1. Frequency Converter Usage CHALCO Shanxi Branch has used various frequency converter models, including FRENIC 5000G9S, 5000P9, 5000G11S, 5000P11S, and Siemens MICROMASTER Eco series and MID1MASTEREco series. Currently, the frequency converters used by the Shanxi Branch are primarily PWM (Pulse Width Modulation) type frequency converters. A PWM frequency converter is an AC-DC-AC converter, consisting of a rectifier, an intermediate stage (DC circuit), and an inverter circuit. The rectifier circuit converts the mains frequency AC power into DC power. After passing through the intermediate stage, the inverter converts the DC power into AC power with an adjustable frequency for the load. PWM frequency converters often use voltage-source inverters. The basic principle is to control the magnitude and frequency of the AC voltage by controlling the on and off times of the inverter's switching elements. By controlling the on and off of the inverter's switching transistors, a rectangular square wave voltage waveform of unequal width can be obtained in the output circuit. The area of ​​the rectangular square wave voltage is close to that of a sine wave voltage, and the inverter output voltage is close to the fundamental voltage, with higher harmonic voltages greatly reduced. Its output waveform is relatively good, making PWM frequency converters particularly suitable for asynchronous motor speed control. The various frequency converters used by China Aluminum Shanxi Branch are fully functional and have comprehensive protection features. Taking the FRENIC series as an example, this type of frequency converter is not only relatively complete in terms of basic functions, extended functions, and frequency control functions, but also has a Chinese menu and both LCD and LED displays. It is very convenient to use. However, over the years, due to the lack of basic professional knowledge and operating skills among operators and maintenance personnel, they often encounter various problems that they cannot handle, and some have even resorted to destructive repairs and operations; some frequency converters only function as soft starters in actual use, resulting in a waste of resources. The following is an analysis and discussion of several common problems. [b][align=center]For details, please click: Problems and Solutions in the Use of Frequency Converters[/align][/b]