Abstract : This paper discusses the inspection and maintenance of frequency converters in practical applications, including pre-power-on inspection, power-on inspection, daily inspection, periodic inspection, and maintenance work such as component replacement cycle, replacement requirements, and long-term storage. Keywords : Frequency converter; inspection; maintenance. Frequency converters are widely used in various fields due to their advantages of energy saving, ease of use, and high degree of automation. Although new frequency converters are fully functional and highly reliable, improper use and maintenance can still lead to malfunctions and affect their service life. Therefore, daily maintenance and related inspections of frequency converters are necessary. We have summarized some experiences in our long-term practical work for the reference of our colleagues. I. Pre-Power-on Inspection of Frequency Converters For newly configured or long-term outdated frequency converters, the following steps should be performed before powering on them for testing. 1. Parameter Check. Carefully check the frequency converter model, rated capacity, rated voltage, and compatible motor power to ensure consistency, especially the rated voltage. 2. Visual Inspection. Open the inverter's panel and visually inspect the internal components. Check for cleanliness, moisture, foreign objects, and blocked ventilation ducts. Pay special attention to cleaning the dust and dirt accumulated on the control circuit board to avoid malfunctions. Check screws, nuts, and connectors for looseness or damage. 3. Wiring inspection. Carefully check the wiring of each terminal on the frequency converter to ensure it is correct. For frequency converters with alternating input terminals (R, S, T) and output terminals (U, V, W) (i.e., R, U, S, V, T, W arrangement) (such as the JP6C-T9 series), verify the accuracy. For frequency converters with input and output terminals arranged horizontally (such as the TD2000 series), prevent the power cord from being mistakenly connected to the output terminal. Terminals marked DB+, DB-, P, and N are for connecting external braking units and should not be connected to the power supply or motor. II. Frequency Converter Power-On Check After completing the pre-power-on checks, a power-on check should be performed. The specific steps are as follows: [b][align=center]For details, please click: Frequency Converter Inspection and Maintenance[/align][/b]