What is ISO 13849?
ISO 13849 (in full: ISO 13849-1:2015) is an international standard for the safety of machinery control systems. It describes how to design, analyse and validate safety functions within electrical, electronic or pneumatic systems.
ISO 13849 determines whether a machine safety circuit is reliable enough to mitigate risks.
The standard is applied worldwide in machine building, the process industry, automation and robotics.
🎯 What is the purpose of ISO 13849?
- Designing safe control systems (e.g. e-stops, interlocks, light curtains)
- Risk-based assessment of the reliability of safety functions
- Compliance with the (EU) Machinery Directive
- Demonstrating an appropriate Performance Level (PL) per function
- Helps ensure the safety of people and installations
🧠 What is a Performance Level (PL)?
A PL indicates how reliable a safety function must be in order to sufficiently mitigate a particular risk.
| PL level | Reliability | Application |
|---|---|---|
| PL a | Low | Minor injury risks |
| PL b–c | Moderate | Limited injuries |
| PL d–e | High / very high | Serious injuries or life-threatening |
Each safety function is designed to achieve at least the required PL, based on a risk assessment.
🧱 What determines the PL?
| Factor | Explanation |
|---|---|
| Category (Cat) | Architecture of the system (e.g. redundancy, detection) |
| MTTFd | Mean Time To Dangerous Failure |
| DC (Diagnostic Coverage) | Degree of fault detection within the system |
| CCF (Common Cause Failure) | Measures against simultaneous failures from a single cause |
Together these elements form the PL calculation in line with ISO 13849-1.
🔧 Examples of safety functions
| Function | Description |
|---|---|
| Emergency stop | Motors stop immediately on press |
| Door interlock | Machine stops as soon as the guard is opened |
| Two-hand control | Operator must press both buttons (e.g. press) |
| Safety light curtain | Stops motion as soon as someone breaks the curtain |
| Overspeed protection | Machine stops when safe speed is exceeded |
🔗 ISO 13849 vs. other standards
| Standard | Application |
|---|---|
| ISO 13849 | General machine safety, widely used |
| IEC 62061 | Safety based on functional SIL |
| ISO 12100 | Risk assessment of machinery |
| IEC 61508 | Foundation standard for functional safety (industry-wide) |
✅ Benefits of applying ISO 13849
- Standardised approach to machine safety
- Demonstrable reliability of safety functions
- Compliance with CE marking / Machinery Directive
- Supported by tools such as SISTEMA for PL calculation
- Applicable to electromechanical and programmable systems alike
📌 In summary
ISO 13849 is the standard for designing, assessing and validating machine safety functions based on Performance Levels. With it, you demonstrate that your machine meets the required safety and reliability requirements.