Abstract: This paper introduces the problems and necessity of modification of the K6/1000 rope-making machine, provides the wiring diagram of the control system, and selects the SJ300 frequency converter with sensorless vector control function to drive the equipment, making the control system speed adjustable, safe and reliable in operation, and achieving the purpose of modification. The parameter setting, debugging process, and precautions are also explained. Keywords : Rope-making machine; Variable frequency speed regulation; Wound motor 1. Equipment Status The K6/1000 rope-making machine is one of the main pieces of equipment in the wire rope production of Ningxia Hengli Wire Rope Co., Ltd. Its drive motor is an AC wound motor, model JR92-8, with a power of 40kW. The starting method uses rotor series resistance, which results in a large starting current that greatly impacts the equipment and can easily cause damage. In actual production, the production equipment is frequently started, such as when loading and unloading I-beams, wire rope production heads, and adjusting the tension of the wire frame, requiring starting and jogging operations. When the K6/1000 rope-making machine is fully loaded, its total mass reaches st, resulting in significant starting inertia. Frequent starts and jogging easily cause cracks in the main gearbox housing, leading to severe leakage of lubricating oil. Ultimately, the only solution is to replace the housing. 2. Equipment Modification To meet production process requirements, retain existing operating habits, and ensure smooth motor starting and speed regulation, AC variable frequency speed control is the optimal solution. Adding PLC process control further enhances reliability. 2.1 Variable Frequency Drive Selection The K6/1000 machine experiences significant starting inertia when fully loaded. Considering the principles of low frequency, high torque, and economy, the Hitachi 51300 variable frequency drive was selected. This series features advanced sensorless vector control, providing 150% of rated torque near 0Hz, meeting the requirements for low speed and high torque. [b][align=center]For more details, please click: Variable Frequency Control of Rope-Making Machine[/align][/b]