What is IEC 62061?
IEC 62061 is an international standard that sets out requirements for the functional safety of electrical, electronic and programmable electronic control systems in machinery. The standard supports the design and validation of safety functions based on SIL levels (Safety Integrity Level).
IEC 62061, like NEN-EN-ISO 13849, is recognised under the Machinery Directive and is an important guideline for Safety PLC applications.
🧠 What does IEC 62061 cover?
- Risk analysis and SIL determination
- Determining the required SIL (1 through 3) per safety function
- Based on severity of injury, frequency, exposure and likelihood of avoidance
- Specification of safety functions
- Description of function, response speed, fault tolerance and reliability level
- Design and implementation
- Redundancy, fault detection, secure communication
- Component selection: Safety PLC, safety relays, sensors, actuators
- Validation and verification
- Documentation of architecture, fault analyses and reliability (PFHd)
- Testing and simulating safety responses
🏭 Application in industrial automation
IEC 62061 is used for:
- Complex machines with programmable control (e.g. Safety PLC)
- Production lines with multiple safety zones and diagnostics
- Applications with high reliability and fault-tolerance requirements
- Integration of emergency stops, speed monitoring, door interlocking and more
Typical sectors:
- Automotive, food & pharma, robotics, metalworking, logistics
🔍 SIL levels explained
| SIL | Average failure rate (PFHd) | Application |
|---|---|---|
| 1 | 10⁻⁶ to <10⁻⁵ | Simple applications, low consequences |
| 2 | 10⁻⁷ to <10⁻⁶ | Most common level in industry |
| 3 | 10⁻⁸ to <10⁻⁷ | Critical functions with high injury potential |
SIL 4 exists, but is rarely used on machines – more so in the process industry.
🔐 Security aspects
- Components must meet the appropriate SIL capability
- Use redundant circuits, fault detection and secure communication
- Validation through calculation of PFHd and analysis of SFF (Safe Failure Fraction)
- Lock-out Tag-out and work permits are required when maintaining SIL systems
- Periodic verification required as part of RI&E and Audit
SIL is quantitative, whereas the Performance Level (PL) from ISO 13849 is more semi-qualitative. The two standards are increasingly compatible.
📌 In summary
IEC 62061 is the standard for the design and validation of safety functions based on SIL in industrial machinery. It provides a structured approach for delivering reliable and fault-tolerant systems.