Rolling mill run-out table automated control system

Transresch Antriebssysteme Berlin GmbH, Germany, manufactured and delivered frequency converters with all the characteristics of the most up-to-date converter units for control of rolling table motors. Features of the frequency converters:

• cabinet execution, ready to connect, with built-in power fuses, disconnector, input reactor, radio frequency interference filter, output sinusoidal filter;
• possibility to implement single-motor and multi-motor asynchronous drives;
• provide stable without breakdown motor and generator operation modes, braking with energy recuperation into supply network;
• have sinusoidal input current with possibility to regulate power coefficient from - 0,8 to + 0,8;
• provide control and information interchange via Profibus DP serial interface;
• provide high dynamics, moment reverse within under 2 ms, with complete provision of all drive features in 4 quadrants;
• provide complete diagnostics of all systems, with out-of-specification situations storage, emergency trace, with all the needed protections for converter and motor.

The main function of the developed system was generation and distribution of speed task (correction) signals between frequency converters of each collecting rolling table group, control of rolling table sections during strip transportation in different modes and signaling about equipment condition.


According to assigned task control system provided:

• constant data exchange between PLC control system, rolling table and control system condition data collection, processing and analysis;
• generation of controlling impacts, transfer (signals, commands) for execution;
• technological signaling, needed parameters and coefficients displaying;
• operational speed parameters input and changing, operational system setting parameters changing;
• control of technology observance by control system operators with necessary interlockings and limitations, protection against inappropriate actions of personnel, unauthorized tampering;
• control algorithms in different operation modes, including “speedup”, “stop”, “speed jam”, “slow down” algorithms;
• diagnostics with place, kind and reason indication of rolling table and control system irregular functioning;
• system operation logging, registration and storage of information concerning pre-emergency status of control system and frequency converter in operation (“emergency trace”);
• intuitive graphic interface;
• upkeep of universal time in the whole system.

Drives are controlled by control system and frequency converters controller parts (control system and frequency converter PLC). Rolling table groups drives control is parallel and independent, i.e. control system PLC simultaneously generates control signals and interacts with all frequency converter РLС, which take part in operation.

Control system PLC is based on B&R SYSTEM 2003 and 2005 controllers. Control system PLC includes two control cabinets, one of them is stand-by, three control panels and six cabinets with controllers for collection of data concerning condition of remote inputs (PLC RIO).

Each control cabinet is equipped with programmable logic controller (PLC) and controller with display panel (DP PLC). Stand-by control cabinet is in hot standby, it switches automatically to the operation mode and can start operation at any moment instead of main control cabinet without any additional settings.

Three operator’s control panels are located along rolling mill. Each of 3 control panels is equipped with DP PLC, allowing full-function control from any of control stations.

Six PLC RIO are located along rolling table, directly near the cabinets with rolling table group motors automatic switches.

B&R Automation Studio 2.10 (AS) was used for software development. AS allows developing intelligent data collection and processing systems. “C” language was used for control system programs development. B&R Fieldbus Configurator was used for integration of control PLCs into Profibus DP network.

System implementation was carried out on constantly operating object — rolling table was available for adjustment for 15–20 minutes 1–2 times a day.

In some cases, models with Borland C++Builder 5 package were developed for especially complicated algorithms debugging.

The following principles were observed while software formation:

• functional sufficiency (completeness);
• reliability and validity (compliance with the given operation algorithm, incoming data control and filtering, no false operations);
• construction modularity and encapsulation (software is divided into tasks, each task functions only with its data);
• multitasking (simultaneous fulfillment of several programs);
• hierarchy (different programs priorities);
• adaptability and flexibility (fast configuration and fast control algorithms rearrangement possibility);
• modifiability (modification and extension, updating, development and growth possibility);
• serviceability and maintainability.