Abstract : Taking an early DC-driven panel paper machine as an example, this paper introduces the application of Senlan SB80 engineering vector control inverter and common squirrel cage motor in the replacement and upgrading of old equipment. Keywords : Senlan SB80 inverter, squirrel cage motor to replace DC motor, vector control, multi-speed range and MOP mode speed adjustment . 1 Introduction Early paper machines, printing presses, and most industrial equipment and transmission systems with high requirements for speed regulation and control used DC regulation and control devices to drive DC motors for speed regulation and control. Most DC regulation devices are analog devices, which are difficult to debug, have poor stability, and a high failure rate. DC motors suffer from high losses in brushes, commutators, and tachometers, all characterized by hard contact wear. This results in poor interchangeability, poor stabilization cycles, high failure rates, long maintenance times, high difficulty and cost, low equipment efficiency, and significant impact on production capacity. Such equipment still accounts for a considerable proportion of the domestic market. In the past decade, AC variable frequency speed control technology has matured, and AC variable frequency speed control is replacing DC speed control as a development trend. This article uses a DC-driven paperboard machine manufactured in 1995 as an example to briefly introduce the application of the Senlan SB80 engineering-type vector frequency converter in the replacement and upgrading of old equipment. [b][align=center]For more details, please click: Application of Frequency Converters in the Replacement and Upgrading of DC Drives in Paperboard Machines[/align][/b]