Realisation of category 3 according to EN 954-1 by use of programmable logic controllers (PLC) - examples

Status:

completed 11/1994

Aims:

Contacts established by the BIA on demand of the BG expert committee for the printing and paper converting industry with manufacturers requiring expert advice revealed large difficulties on the manufacturers' side in complying with the requirements of the European draft standard prEN 1010 "Safety of machinery - Requirements for the design and construction of printing and paper converting machines" as well as with the "Safety guidelines for controls of printing and paper converting machinery" issued by the German Berufsgenossenschaften (BGR 124, former ZH 1/170); these problems concern especially computer-controlled machines and plants. The project was aimed to develop concepts of connection and provide a number of concrete connection examples to illustrate the incorporation of protective devices, the deenergising of drives with electronic power equipment and the satisfaction of requirements resulting from different modes of operation. Another aim was to clearly identify the consequences stemming from the European safety regulations applying to machinery of the printing and paper converting industry.

Activities/Methods:

The examples of printing and paper converting machines without regular intervention in dangerous zones is chosen to illustrate how category 3 - as specified in EN 954-1 "Safety of machinery - Safety-related parts of control systems" - can be realised using standard programmable logic controllers. Concepts of connection and concrete connection examples were presented to demonstrate the incorporation of protective devices, the deenergising of drives with electronic power equipment and the satisfaction of requirements resulting from different operation modes. The use of programmable logic controllers being widespread, a large number of industries face the described problems. The suggested solutions can be used analogously by all of them.

Results:

It was possible to develop several connection concepts and concrete examples of connection in diverse redundancy using standard PLCs. It was thus demonstrated how the safety functions specified in prEN 1010 can be realised:

• Connection concepts with "cold" redundancy.
• Connection concepts with partial, functional redundancy by computer or PLC.
• Connection concepts with partial, functional redundancy by relay technique.

A detailed description of all connection examples is given. In addition, the most important requirements in terms of control technology as referred to in prEN 1010 and EN 60204 "Safety of machinery - Electrical equipment of machines" are summarised and supplemented by information regarding their implementation.

Further informations:

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