1. The paper machine is composed of headbox, wire section, press section, drying section, calender, roll paper and other parts. 

The main transmission electric control system is a speed chain coordination system composed of multiple transmission points.

2. A fixed transmission ratio should be maintained between each transmission point to keep the line speed of each transmission point consistent. 

It is convenient for the equipment to speed up and decelerate, and avoid paper breakage or stacking due to the large difference in line speed between the transmission points.

3. The low-speed paper machine requires a control accuracy of 0.1% for the speed regulation of the transmission system, and usually requires a frequency control accuracy of 0.01HZ.

4. The analog signal is susceptible to electromagnetic interference, which affects the transmission accuracy and stability of the paper machine. 

In order to improve the accuracy and stability of the system and enhance the anti-interference ability, the system uses PLC as the main control unit, 

and the acceleration and deceleration at all levels are controlled by buttons; Calculation and control, through RS485 communication, 

send speed adjustment instructions to the frequency converter by means of data.

EM303A series open-loop vector control frequency converter, N sets, has the advantages of high transmission precision, good dynamic performance and fast response speed.

System main control unit: Mitsubishi FX2N series PLC with 485 communication module and D/A module.

Each transmission point of the system is controlled according to the speed open loop mode, and the speed control command is issued by the PLC.

1. The electric control system adopts an open-loop control method, with simple structure, clear control logic relationship, safe and reliable use, and convenient operation and maintenance.

2. Current vector control frequency converter, flexible speed control, fast response, high efficiency and good dynamic performance.

3. The frequency accuracy of the frequency conversion speed regulator is 0.01HZ, the system speed regulation accuracy is high, and there is no drift and zero error.

4. PLC control is adopted to accurately calculate the speed transmission ratio of each level, and the speed coordination control accuracy between each transmission point is high, 

and there will be no paper breakage or paper stacking.

5. The communication method realizes the full digital control of the system, with strong anti-interference ability and no signal attenuation.

6. The current speed of each level is automatically stored during the running process. When the machine is stopped or restarted after a power failure, the system runs at the speed before the stop,

and there is no need to readjust the set speed of the frequency converter at all levels.