Machinery safety
IEC 62061
The machinery-sector application of IEC 61508: design, integrate and validate safety-related control systems to SIL 1–3.
Safety of machinery — Functional safety of safety-related control systems
- Category
- Machinery safety
- Scope
- International
- Edition / refs
- IEC 62061:2021 (EN IEC 62061)
MSA output
- PLr / SIL calculations
- Validation protocols
- Fault injection tests & device test records
- Safety matrix (FAT/SAT)
What is IEC 62061?
IEC 62061 is the machinery-sector implementation of IEC 61508. It specifies requirements for the design, integration and validation of safety-related control systems (SCS) for machinery, using Safety Integrity Levels SIL 1 to SIL 3.
Since Edition 2 (2021), IEC 62061 is no longer limited to electrical systems: it applies to safety-related control systems of any technology. It covers SIL assignment, decomposition into subsystems, the probability of dangerous failure per hour (PFH), architectural constraints, safety-related software and functional safety management.
Who it applies to
- Machine builders with complex or programmable safety functions
- Integrators building safety systems around safety PLCs and networked devices
- Organisations already working with IEC 61508 concepts
- Engineers whose customers specify safety integrity in SIL
Key requirements
- 01
Functional safety plan
Plan activities, responsibilities, verification and documentation across the control system life cycle.
- 02
Safety requirements specification
Define each safety function, its required behaviour and its SIL requirement.
- 03
Assign SIL
Derive the SIL from severity (Se) and a class based on frequency and duration of exposure (Fr), probability of the hazardous event (Pr) and possibility of avoidance (Av).
- 04
Design subsystems
Decompose functions into subsystems; apply architectural constraints using hardware fault tolerance and safe failure fraction or diagnostic coverage.
- 05
Verify PFH
The total PFH of each function must meet its target: below 10⁻⁵/h for SIL 1, 10⁻⁶/h for SIL 2 and 10⁻⁷/h for SIL 3.
- 06
Validate
Confirm by analysis and testing that every safety function meets its specification.
Summary for orientation only. Always refer to the current official text of IEC 62061 and any applicable legislation.
MSA for IEC 62061
What MSA generates
Evidence produced from your engineering inputs, traceable end to end and exported to Word, PDF or Excel.
PLr / SIL calculations
SIL assignment per safety function, traceable to the hazards in the risk assessment.
Validation protocols
Structured validation plans and records for each safety function.
Fault injection tests & device test records
Test procedures and per-device records supporting verification of the control system.
Safety matrix (FAT/SAT)
Safety functions mapped to factory and site test steps, with results and sign-off.
Frequently asked questions
Should I use ISO 13849-1 or IEC 62061?
Both are harmonised for machinery and, since IEC 62061:2021, both cover any technology. ISO 13849-1 with its designated architectures is often simpler for typical machine safety functions; IEC 62061 suits complex programmable systems and teams already using IEC 61508 concepts. See our guide to choosing between them.
Why does IEC 62061 stop at SIL 3?
SIL 4 is not considered relevant to the risk reduction requirements normally associated with machinery, so IEC 62061 covers SIL 1 to SIL 3 only.
Can I combine subsystems designed to ISO 13849-1 in an IEC 62061 function?
Yes. IEC 62061 allows subsystems designed to ISO 13849-1 to be integrated using their PL and PFH values, which is common when using certified safety components.
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