Abstract : This paper mainly introduces the application of frequency converter in the reform of domestic single-double-color singleton paper lithog raphy machine, and some functional requirements for the frequency converter. Key words: Lithography machine Inverter 1 Introduction Currently, new electrical control technologies have been widely applied to domestic single-sheet lithog raphy machines, such as PLC, touch screen, and frequency converter. Compared with older models from several years ago, these new single-sheet lithog raphy machines have advantages such as high reliability, energy efficiency, and complete functions. However, in many printing companies, there are still a considerable number of old-model single-sheet lithog raphy machines. If they are to be upgraded to use PLC and touch screen, a large number of circuits need to be changed, which is almost equivalent to rebuilding the electrical control system. If only the main drive part of the single-sheet lithog raphy machine is upgraded using a frequency converter, the circuit changes are small and the workload is less. This approach retains the simplicity and practicality of the original relay contact control while fully leveraging the reliability and energy-saving advantages of frequency converters, resulting in a high cost-performance ratio. The following discusses some experiences regarding the application of frequency converters in the retrofitting of domestic single-color and double-color sheet-fed offset printing presses. [b][align=center]For details, please click: Application of Frequency Converters in the Retrofitting of Sheet-Fed Offset Printing Presses[/align][/b]