Measurement and control system OPTIPA for continuous webs is conceived as modular system. There are three main and independent modules which can make up the system:

• 1) Measurement of web parameters

• 2) Visualization of the production process

• 3) Control of the production process

Measurement of web parameters

This basic module consists of several key components:

• special devices for measurement of following qualitative parameters of produced web:





• moisture

• sensors working on principle of scattering of infrared radiation

• sensors working on principle of absorption of microwave radiation

• basis weight
  (whole product or selectively particular layer)

• sensors working on principle of absorption of beta and gama radiation

• sensors working on principle of scattering of infrared radiation

• thickness
  (whole product or selectively particular layer)

• sensors working on principle of absorption of beta and gama radiation

• sensors working on principle of scattering of infrared radiation

• sensors working on principle of optical measurement (triangulation principle)

• sensors working on principle of eddy currents

• evaluation units for the special measurement devices

• measuring frames for fixing the measurement devices (traversing C-frames, O-frames or I-frames eventually non-traversing frames/brackets for measurement in a fixed position)

All mentioned components are connected with the switchboard which contains PLC with the made-to-measure application software OPTIPA. The main task of the PLC is to read and to evaluate signals from all components of the system (i.e. from measuring devices, photocells, magnetic transducers of end position etc.) and to execute basic control operations (control of movement of the scanning frame, control of shutter of radioactive devices etc.). It is also possible to incorporate necessary light or audio signal components and digital displaying instruments into this module.


Visualization of the production process

The key-stone of this module is an industrial PC with visualization software Citect (including its hardware key). If required, a laser or ink printer can be included. The industrial PC communicates with the PLC via standard communication means (RS232 or RS422). Within the Citect environment there is application software OPTIPA running. This application software can contain many functions - for example:

• overview of the production technology which includes displaying of prompt values of measured web parameters (moisture and/or basis weight and/or thickness) and eventually displaying of other variables from the production process (e.g. temperatures, flow rates, speeds, revolutions etc.)

• displaying of cross profiles of measured qualitative web parameters

• schematic displaying of frame position and components for its control

• calculation and displaying of required statistics of measured parameters (averages, standard deviations, medians etc.) for the frame crossover

• automatic continual saving of trends of measured or calculated variables (within the software Citect) with the archiving period lasting several years

• sophisticated displaying of trends of selected variables with wide setting possibilities (displayed variables, trend length, end date and end time of the trend, displayed limits for each variable etc.)

• automatic export of trends in *.csv files to the pre-defined place (e.g. company server)

• creation of reports about production, shifts and rolls and their displaying / printing / export to pre-defined place (e.g. company server)

• displaying of actual and historic alarms indicating production breaks or occurrence of out-of-limit conditions or other critical situations

This list of possible functions of the application software OPTIPA isn’t final. Requirements and needs of the customer are always taken into account during the creation of the software. In case of need, application software OTPIPA can whenever be modified or supplemented.


Control of the production process

This module represents the highest level of the system OPTIPA. This level involves control functions that are implemented into the application software OPTIPA that is located in the PLC and also in the industrial PC (Citect). Control of qualitative parameters is possible not only in machine direction but also in cross direction.
Control functions are designed and realized according to type of the production line, into which the system OPTIPA is going to be implemented. It can be generally said that to perform the control functions, the system uses the same actuators that were manually used by the line operators before the implementation of automatic control system.

Example:

System OPTIPA for paper machine or board machine usually contains following basic control functions:

• Control of basis weight by flow rate of feed pulp

• Control of basis weight by speed of the machine

• Control of moisture by vapor pressure

• Control of ash content by flow rate of kaolin

• Control of eflux