As we all know ,the performance of the electrical drive control system of a paper machine is the premise to determine whether a paper machine can produce with high efficiency and high quality. So for a normal paper machine, in order to ensure its continuous production well, the maintenance of the drive system is particularly important.

 How to correctly distinguish the fault of the whole machine?

Electric technicians should take a look at the second test and three tests. At first glance, the reason for the location and phenomenon location of the problem first and the analysis of the comprehensive process process; the second test is to measure the parameters and other parameters observed in observed to exclude the instruction errors; Single -machine tests confirm the general range of electrical or mechanical failures.

What are the identifiable problems of the paper machine drive system?

Electrical fault caused by line fault or communication interference

• The frequency converter cannot be started, and the load is not stuck or locked. The motor heating is abnormal, or even smokes, or the current is large and the motor does not rotate or the torque is small, which may be caused by line fault or internal fault of the motor.

• Operation failure, or abnormal reflection, sometimes good or bad; The load distribution is unbalanced and can be adjusted but the degree of change is unstable.

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Mechanical failure

• Bearing heating

• Abnormal rotating sound of equipment, obvious periodic sound and mechanical cycle can be observed

• The common mechanical failure of the mesh part is the slippage of the mesh drive roller, which is manifested as good or bad load distribution, especially abnormal acceleration.

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What is the problem of paper machine drive system that is difficult to determine?

There are four factors affecting the speed instability

• Speed sensor (generally encoder) mechanical connection is poor, the connector should be checked.
• The load of mechanical equipment has changed greatly. Open the connector with mechanical equipment and only run the motor to determine whether the interference comes from mechanical equipment.

• The speed regulator parameters are not appropriate. Check and adjust the speed regulator parameters.

• When the wet end of the paper machine starts to draw paper, the moisture content of the paper web is often too high, and the weight of the drooping part of the paper web will elongate the paper web when drawing paper. Therefore, it is always considered that the speed of the rear part is too slow. In fact, the faster the speed of the rear part is, the more serious the drooping phenomenon is. The dehydration condition of the corresponding part should be checked and adjusted.

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Speed mutation is the second reason for the failure of the paper machine transmission system

• The mechanical connection of the speed sensor is poor, and the connector should be checked.
• The connection point of the line is in poor contact, and the wiring should be checked.
• Mechanical equipment failure, such as bearing damage.

Large load fluctuation is the second reason for the failure of the paper machine transmission system

• The mechanical connection of the speed sensor is poor, and the connector should be checked.
• The load fluctuations in mechanical equipment are large, and the joints of the mechanical equipment should only run the motor to determine whether the interference comes from the mechanical equipment.

Solutions for two cases

Paper -breaking inside the cylinder is not the most important reason

The paper break inside the drying cylinder must be related to the process parameters such as steam pressure, paper weight and slurry composition. Even if there may be speed fluctuation, it is not the main problem. Therefore, it is necessary to assist the process personnel in finding other reasons.

Broken paper at the press section is a fault difficult to judge

The paper breaking at the press section is a relatively difficult fault to judge. Generally speaking, it should be analyzed and judged according to the press form and the paper breaking position.

The main method to judge the compound press is to observe whether the current indication is normal and the swing size. If serious imbalance or abnormal oscillation is found on the ammeter, the no-load commissioning shall be carried out first to find the cause of imbalance and adjust the parameters to stabilize the system.

What is the reason for the instability of a single roller?

Check whether the connecting lines have poor contact, especially the associated signal lines, such as feedback lines, communication lines, input and output lines between load distribution points, etc.The PLC program checks whether the upper and lower limits of the set parameters are appropriate, whether the calculation program is correct, and whether the program is executed correctly.Check whether the torque compensation is set reasonably and whether the default parameters are consistent with the motor parameters.

Whether the motor is normal, there are abnormal sounds and abnormal heat. If the above is normal, the electrical is normal, and observe the causes of process and raw materials.

Paper-breaking at the connection between the network and the squeezing department is easy to make mistake

This is closely related to the variety of paper and the composition of raw materials. The causes are more complex, and it is easier to make mistake.

If the press is accelerated after the paper is found to be sagging, it will break when the paper is just seen to be lifted. Or when there is a lot of sag, it is too late to accelerate. On the surface, it seems that the speed regulation is out of order, which will cause judgment error. This situation requires the electrical personnel to repeatedly observe the speed and current indication to conduct in-depth analysis and comprehensive judgment, and do not blindly draw conclusion.

Why should electrical workers have some knowledge of paper making technology?

During the operation of the paper machine, because the mechanical and electrical are closely connected, some faults are obvious, and some faults are difficult to determine whether the fault source is electrical or mechanical, This requires electrical personnel to be familiar with the electrical system, and at the same time have some relevant knowledge of paper making technology. When encountering problems, they should comprehensively analyze and repeatedly test.