Abstract : This paper discusses some effective inspection and maintenance experiences summarized by the author in many years of field operation and practice with Mitsubishi frequency converters. These experiences are highly practical and operable, and can provide important reference and guidance for the inspection and maintenance of other types of frequency converters. Keywords : Frequency converter, inspection and maintenance 0 Introduction With the development of modern electronic technology, the performance of AC motor speed control frequency converters is constantly improving. Due to their advantages such as wide speed range, high precision, fast dynamic response, high operating efficiency, high power factor, convenient operation, and easy connection with other equipment, frequency converters are becoming increasingly widely used. However, as they are static machines with semiconductors as their core, in order to prevent failures caused by environmental factors such as temperature, humidity, dust, vibration, and the aging of parts, which could affect the normal operation of the equipment, it is necessary to conduct regular necessary inspections and maintenance. The following are some effective inspection and maintenance experiences and methods summarized by the author in many years of field operation and practice with Mitsubishi frequency converters. 1 Daily Inspection and Maintenance Daily inspection and maintenance refers to checking whether the frequency converter exhibits the following abnormal phenomena during operation. (1) Check if the installation environment is abnormal. Use a thermometer to check if the ambient temperature is between 10-50℃ and not freezing, and use a hygrometer to check if the ambient humidity is below 90% and not condensing. (2) Check if the refrigeration system (refrigeration fan) is abnormal. (3) Check for abnormal vibrations or sounds. (4) Check for abnormal overheating or discoloration. (5) Check if the instrument readings are abnormal. If necessary, use a multimeter to check the input and output voltages of the inverter. [b][align=center]For more details, please click: Inverter Inspection and Maintenance[/align][/b]