What IEC 62061 Edition 2 introduces

Safety-related control systems (called SCSs) implemented as a result of automation play a more significant role than ever in ensuring the overall safety of machinery. These SCSs also use increasingly complex electronic technologies, hence the need to update the IEC 62061 standard.

Content of the IEC 62061 standard

The international standard IEC 62061 specifies the requirements and provides recommendations for the design, integration and validation of safety-related control systems (SCSs) for machinery.

It is applicable to control systems used individually or in combination to perform safety functions for machinery, including a group of machines working together in a coordinated manner.

In fact, IEC 62061 specifies the requirements for the design and implementation of safety-related control systems for machinery. This standard is specific to the machinery sector under IEC 61508.

IEC 62061 uses methodologies that differ from those of ISO 13849-1 for the design of control systems, although with the same aim to reduce risk.

 

The IEC 62061 standard is intended for:

• machine designers
• manufacturers
• control system integrators
• other parties involved in the definition, design and validation of an SCS

In general, it therefore establishes an approach and provides the requirements to achieve the necessary performance and makes it easier to define the safety functions for reducing the risk.

 

Field of application of IEC 62061

SCSs are the “true” field of application of the standard: anything that cannot be defined as part of the safety-related control system is not covered by the standard, even if these parts are installed and used exclusively to mitigate a specific risk.

 

An SCS, Safety-related Control System, is by definition the part of the control system of a machine that implements a safety function with one or more subsystems.

 

 

IEC 62061 Edition 1 vs. Edition 2

In Edition 2, the structure was modified and the contents were updated to reflect the design process of the safety function:

• The standard now extends to non-electrical technologies (it previously applied only to pneumatic and hydraulic technologies)
• The definitions were updated in line with IEC 61508-4
• The functional safety plan was introduced
• The management of configuration was updated
• There is a greater focus on the software, for example in relation to the extension of extended software parameterization requirements (clause 6) and the description of software use cases, including requirements (clause 8)
• Requirements were added for periodic tests (sub-clause 6.9)
• Various improvements and clarifications on architectures and reliability calculations were introduced (clauses 6 and 7)
• The “SILCL” of a subsystem was switched to “maximum SIL“
• There are new annexes on typical MTTFD values, diagnostics and calculation methods for architectures (Annexes C, D and H)
• Independence requirements for software verification (clause 8) and validation activities were added

 

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