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Application of SINOVO SD300 series frequency inverter in the Paper machinery
Paper machinery is the high consumption in the energy power. The Electric energy can be loss 500kw.h for each 1000 kgs papers, It’s very serious in the loss electric energy.
The traditional Paper machinery applied with SCR DC adjust the speed(big power) and Slip motor drive(small power). In the paper production, it will be broken and uneven thickness of the paper for the matched speed imbalance with some mechanical wear, slip of transmission belt problems.
To reduce energy consumption, optimize product quality, improve labor productivity, modern papermaking equipment mostly use multi-motor segment drive, that means each transmission branch is equipped with an AC motor and a corresponding frequency converter. It is required that each branch can achieve synchronous control and also be able to adjust the speed within a certain range.
Now please check the application of SINOVO SD300 series frequency inverter in the Paper machinery for the example of the Jiangsu province Paper machinery company.
II. Papermaking process
The basic components of papermaking machinery are divided into wire section, press, pre-drying, post-pressing, post-drying, calender, roll paper machine, etc. according to the order of paper formation. The process is that the pulp output from the headbox is dewatered in the net section, compressed in the press section to make the paper layer uniform, dried before drying, then pressed into the post-press for sizing, and then dried in the post-dryer, and then used The calender smooths the paper, and finally forms a mother paper roll through a paper winder. The papermaking process flow chart is as follows:
III. System control case
The post-drying, calender and coiler of a papermaking process in a paper mill in Jiangsu originally used DC speed regulation. SINOVO SD300 series inverter now used for multi-motor branch transmission control. The specific control requirements are:
1. All five inverters use closed-loop vector control to increase the control accuracy of the variable-frequency speed regulation and the system's starting capability.
2. The first three dryers and the fourth calender require the same line speed.
3. The fourth calender requires a torque-to-speed conversion (automatic) function. The calender, when running in the torque control mode, can well balance the change in the tension of the paper output from the rear drying roller, thereby effectively preventing the paper surface from slipping during calendering. At the same time, it also provides a good winding side. Paper feed conditions.
4. The fifth unit is a paper rewinding control (roller). The tension is required to be constant during rewinding. There is no tension feedback in the system. Therefore, tension-free feedback torque control mode is used to control the paper rewinding position.
The electrical wiring diagram of the control system shown as below
IV. System advantages
(1) The frequency converter is small in size and light in weight, no additional control panel is needed, easy installation, simple commissioning, convenient operation, low noise and no vibration. Zh
(2) The speed regulation accuracy is high. When the load and network voltage change (340-420V), the motor speed does not change, so the adaptability is very strong.
(3) It has a complete protection function and high integration, so it has high reliability. The inverter has a self-diagnostic function, convenient maintenance, greatly reducing the downtime, and naturally increases the production output.
(4) It has good power-saving fruits, which can save about 30% of electricity, and it can recover all the investment costs in about 6 months.
(5) Realize stepless speed regulation, small starting current, no impact on machinery and power grid, very suitable for soft-start equipment, such as rewinding machine, calender, etc.
V. Application pictures
SD300 has PG vector (closed loop vector) variable frequency speed regulation scheme, which can well meet the control requirements of speed setting, speed fine adjustment, acceleration and deceleration control, speed / torque switching, load distribution, and rewinding during the paper production process. Due to the use of the SD300 high-performance vector inverter, the system has the characteristics of large starting torque, strong overload capacity, fast dynamic response, and high stability speed accuracy. SD300 provides a perfect solution for papermaking machinery, reduces energy consumption, improves production efficiency, saves users more costs, and has been more and more widely used in the medium and low speed papermaking industry.