line synchronisation

Dear All,

400 Hp DC motor along with control technique mentor II drive is used for line shaft application of paper plant and in which different sections such as press section , dryer section, etc is attached and being operated through pneumatic clutch.

We have separated the press section of 160 KW from that line shaft and it is being driven by individual secitonal drive of ABB make type ACS 800, which is being synchronised with existing line shaft 400 HP motor through siemens make PLC S7 314, via line reference encoder of 1024 PPR and also the press sectional drive motor is running in close loop system by feedback encoder.

Problem is that when the line is running and some section on the line shaft is stopped or re-started the paper synchronisation between both the drives get affected as during penumatic clutch engage and disengage time a huge load is being added or released.

Thus this problem is related to PID gain setting or some another remedial action can be adopted to avoid this type of problem.

dwivedi.

This sounds like an excellent example of the difference between speed regulation and position regulation.

No matter how tight you set up the speed regulator, it has no way of reestablishing the proper positioning of its section once the clutch is opened and re-closed.

In my opinion, your S7 controller needs to be capable of position regulation. That way, when the positioning is disturbed (paper sheet too tight or loose), the controller can instruct the drive to move ahead or fall back to re-establish the position relationship it had.

I would strongly recommend you find a local system integrator with paper machine experience. Paper machine tensioning is extremely demanding and nothing can take the place of lots of experience in making these systems work right.

put the encoders on the paper and have somewhere some slack