How to safeguard your mission critical application, a focus on IEC 61508

tunne_automationToday, many routines and products from our daily lives are based on technology driven processes. Each process demands for control solutions to meet the specific process requirements in the first order. But regardless of the pure fulfillment of these functional requirements there is very often potential for hazards which may arise from the process in specific situations or along with its specific boundary conditions.

Just think of a traffic management system, which orchestrates the masses of vehicles on the streets and crossings, or in tunnels. Reliability is key to maintain coordination for a smooth traffic flow or to launch emergency programs, once an incident is recognized.

In another case it could be a chemical reactor which requires tight physical monitoring and, in case of abnormal behavior, a reliable control sequence for an immediate shutdown procedure.

For a production machine or a robot cell, physical operator interaction may be required from time to time. Any kind of uncontrolled machine behavior can lead to threatening situations for the operator.

All the examples mentioned above call for specific considerations and measures to cope with potentially hazardous situations. Any kind of malfunction could lead to severe damage to specific assets or even threaten human lives. This calls for concepts to guarantee functional safety.

A generic standard for functional safety: The IEC 61508

A number of standards and methods have been published to address the need for functional safety in industrial applications. The international standard IEC 61508 provides a comprehensive framework for the systematic conception, development, verification and validation of applications under consideration of the “Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems” (E/E/PES).

The IEC 61508 is a generic standard. It is not specifically bound to any industry. There are, however specializations of the standard, such as:
•    EN 50129 Railway Applications – Communication, Signaling and Processing Systems
•    EN 62061 Safety of Machinery
•    ISO CD 26262: Road Vehicles – Functional Safety

The IEC 61508 defines the required engineering measures to take whenever electric, electronic and software components are utilized to control process components, the so called “Equipment Under Control” (EUC). This of course becomes specifically relevant, once an application involves potentially dangerous situations. The “Safety Integrity Level” is used as a measurement to indicate “how dangerous” specific conditions can get and, in turn, how sophisticated respective countermeasures have to be.

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