0 Introduction This system utilizes the Siemens USS protocol format to achieve communication between the PLC and the Siemens 6SE70 vector frequency converter, completing functions such as the speed chain structure and load distribution control of the paper machine. It achieves high control accuracy and stability in the paper machine drive, fully meeting the needs of paper machine production. When designing the electrical control system of this paper machine, considering it was a system upgrade project, the principle was to meet both the reliability and good control accuracy and stability of the paper machine drive control system, while also reducing the cost of the control system. We selected a Siemens S7-226 PLC and a Siemens 6SE70 all-digital multi-functional vector control frequency converter, using the USS protocol communication format to achieve communication between the PLC and the frequency converter, forming the control system for this machine. The 6SE70 vector control frequency converter has excellent drive performance, adopts an advanced rotor magnetic field vector control strategy, uses IGBT devices for power components, and offers a wide range of electronic modules to choose from. Advanced control software ensures optimal dynamic response, excellent control performance, and high flexibility. Multiple free-function modules and BICO technology can flexibly meet the control system needs of various control functions. The Siemens 6SE70 vector control function can achieve high-precision vector control for different motors. In particular, the vector control mode with PG has extremely high speed control accuracy (+0.01%) and extremely high starting torque (150% at 0.00/min). When used in conjunction with a PLC, it can realize functions such as speed chain control, automatic load control, speed difference control, and tension control. [b]1 Requirements of the paper machine drive for the electrical control system 1.1 Brief introduction of the machine structure[/b] This paper machine is a 1760/250m/min long-wire multi-cylinder cultural paper machine, producing 40-65g/m high-grade cultural paper with a steady-state accuracy ≤0.01%. The original control system adopted an early DC speed regulation control system. Due to the aging of components and the increase in service time, the control system of this machine can no longer meet the needs of normal production. This paper machine consists of a long-wire section, a vacuum suction + four-roll two-pressure zone composite press section, a drying section, a sizing section, a calendering section, and a winding section. There are 16 drive points in total, with a total power of 324kW. The power of each drive point and the inverter model are shown in Table 1. [b][align=center]For details, please click: Application of Siemens 6SE70 Inverter in a 1760/250m/min Paper Machine[/align][/b]