Overview

Functional safety of machines and plants – Basic safety requirements in the manufacturing industry

In order to protect people and the environment in many industrial applications in the manufacturing and process industries, machines and plants must meet the fundamental safety requirements of the EU Directives, particularly the Machinery Directive. In addition to design solutions, automation systems and components are also expected to perform safety-related tasks. This means that the life and health of people and the physical integrity of capital goods and the environment depend on the proper operation of these systems and components, on "functional safety".

With the introduction of the unified European Single Market, national standards and regulations affecting the technical realization of machines were consistently harmonized. This involved defining basic safety requirements which address, on the one hand, machine manufacturers in terms of the free movement of goods (Article 95) and, on the other hand, machine operators in terms of industrial safety (Article 137).

The EU directives:

• define requirements which must be met by plants and their operating companies in order to protect the health of people and the quality of the environment
• include standards for health & safety at work (minimum requirements)
• define product requirements (e. g. for machines) to protect the health and safety of the consumer
• differentiate between the requirements which must be met by the implementation of products in order to ensure the free movement of goods and the requirements which must be met for the use of products

Safety requirements imposed on machines and plants

Objective of the standards

It is the objective of safety technology to minimize, as much as possible, the hazards created by technical facilities for people and the environment, while restricting the scope of industrial production, the use of machines, or the production of chemical products no more than absolutely necessary.

Production automation is governed in particular by the following standards:

• IEC 61508 or IEC 62061 and
• EN ISO 13849-1

The IEC 62061 standard

The IEC 62061 standard "Safety of machines - Functional safety of electrical, electronic and programmable electronic control systems" defines comprehensive requirements. Furthermore, it issues recommendations for design, integration and validation of safety related electric, electronic, as well as programmable electronic control systems (SRECS) for machines. With the implementation of EN 62061, for the first time, one standard covers the entire safety chain, from the sensor to the actuator. The Safety Integrity Level, or SIL for short, is defined as the application parameter for this standard.

Performance capacity requirements for non-electric safety related control elements for machines – e. g. hydraulic, pneumatic, or electro-mechanical – are not regulated by the standard.

Machine safety

The EN ISO 13849-1 standard

EN ISO 13849-1 "Safety of machines – Safety-related components of controls, Part 1: General principles" replaced EN 954-1 at the end of 2011. It considers the complete range of safety functions with all the devices, which are involved in their performance. EN ISO 13849-1 also makes a quantitative analysis of the safety functions. The standard describes how to determine the performance level (PL) for safety-relevant parts of control systems on the basis of architectures specified for the intended service life.

When combining several safety-related parts to form a complete system, the standard explains how to determine the resulting PL. It can be applied to safety-related parts of control systems (SRP/CS) and all types of machines, regardless of the technology and energy used, e.g. electrical, hydraulic, pneumatic or mechanical.

Safety Integrated – integrated safety technology from one source

Safety Integrated product family

For mechanical engineering as well as operators: Maximum possible safety for personnel and machines. The solution: our safety concept is: Safety Integrated based on Totally Integrated Automation. Whether for simple safety functions or highly complex tasks – our portfolio offers you maximum safety.

Safety Integrated is a unique, complete and consistent range of safety products covering all safety-related tasks – from sensing and evaluating to responding, from industrial control and steering systems to operating mechanisms (see graphic below). Our products meet the safety requirements currently enforced in industry, including IEC, ISO, NFPA and UL, and are certified in accordance with the latest safety standards.

All Safety Integrated products or systems can be seamlessly integrated in the standard automation environment. They are therefore particularly flexible and economical, reduce engineering time, increase plant availability and enable practice-related machine operation.

Designing a safety function

A safety chain normally comprises the following functions: sensing, evaluating and responding. In detail:

• Detection = recognizing a safety requirement, e. g. when an EMERGENCY-STOP is actuated, or someone enters a hazardous area, which is protected by sensors such as light arrays or laser scanners.
• Evaluate = the detection of a safety requirement and the reliable initiation of a reaction, e.g. shutting down the enabling circuits.
• Responding = responding to a hazard, e. g. shutting down a power supply via the downstream contactors.

Designing a safety function

Our offering

As a partner for all safety requirements, we not only support you with the respective safety-related products and systems, but also consistently provide you with the most current know-how about international standards and regulations. Machine manufacturers and plant managers are offered a comprehensive training portfolio, as well as our services for the entire lifecycle of safety-related systems and machines.

• A uniform, certified product range
• For courses on CE marking, risk assessment and standards, see http://www.siemens.com/sitrain-safetyintegrated
• For service and support worldwide, see http://support.automation.siemens.com
• For more information, see http://www.siemens.com/safety-integrated

Safety evaluation tool

Safety evaluation tool

The Safety evaluation tool for the standards IEC 62061 and EN ISO 13849-1 guides you quickly and safely through all the calculation steps in implementing safety functions on a machine, from definition of the safety system structure through to selection of the components. It will investigate compliance with safety integrity step-by-step and online (SIL/PL). The resulting report is standard compliant and can be integrated into the documentation as proof of safety.

The Safety evaluation tool offers the following advantages:

• Time savings during the evaluation of safety functions
• Calculations in accordance with current standards
• User-friendly archiving: Projects can be saved and called up again as needed
• Quick and easy handling: comprehensive, predefined sample libraries
• Quick access to product data
• Import function for safety characteristic values of products of other manufacturers in XML format acc. to VDMA unified sheet 66413
• Selection aids for determining variables and specifying the system design
• Helpful documents which can be downloaded as PDFs
• Free online tool use. You pay only the usual costs for your internet connection.

For more information, see http://www.siemens.com/safety-evaluation-tool.

Safety Integrated

SIRIUS Safety Integrated

Our SIRIUS Safety Integrated controls are a central element of the Siemens Safety Integrated basic concept. Whether for fail-safe identifying, commanding and signaling, monitoring and evaluating or starting and reliable shutting down – our SIRIUS Safety Integrated controls are experts at performing safety tasks in your plant.

SIRIUS Safety Integrated uses fail-safe communication, using standard fieldbus systems, e. g. ASIsafe via AS-Interface and PROFIsafe via PROFIBUS and PROFINET, to solve even networked safety tasks of greater complexity. This opens the door for flexible safety solutions for compact machines or large-scale plants.

SIRIUS Safety Integrated

Monitoring with fail-safe evaluation units from the 3SK and 3RK3 series

Notes:

For more information, see
http://support.automation.siemens.com/WW/view/en/35443942.

For information on safety switches, see Position and safety switches.

Using SIRIUS 3RT contactors with fail-safe controllers and safety relays

Safety relays and fail-safe controllers work perfectly with SIRIUS contactors optimized for safety application regardless of their size:

• For sizes S00 and S00 we recommend 3RT2 contactors with DC operating mechanism.
• 3RT2 coupling contactors with electronic operating mechanisms are available in sizes S2 and S3.
• The innovative 3RT1 versions with electronic operating mechanism and fail-safe control input are ideal for higher power ranges, such as sizes S6 to S12.

They offer the following advantages:

• Reduced current load on the controller outputs
• Minimization of wear for mechanical relays on controllers or safety relays
• Coupling elements between controllers and contactors are no longer required

Combination von SIRIUS 3RT contacts with fail-safe controllers and safety relays

Note:

For an overview table of the SIRIUS Safety Integrated products, see the following PDF.