What is NEN-EN-ISO 13849?
NEN-EN-ISO 13849 is an international standard for the functional safety of machine control systems. It supports the design and evaluation of safety functions such as emergency stops, light curtains or guard detection, and determines the required Performance Level (PL) based on the risk involved.
The standard is crucial for compliance with the Machinery Directive and, together with SIL (IEC 62061), forms the basis for machine safety in industry.
🧠 What does ISO 13849 govern?
- Risk assessment of the machine
- Determining risks based on severity, exposure and avoidability
- Use of a risk graph to determine the required Performance Level (PLr)
- Design of safety functions
- Hardware and software that prevent or limit hazards
- Example: an emergency stop safely shuts down all motion
- Assessment of the Performance Level (PL)
- Based on:
- Component reliability (MTTFd)
- Diagnostic coverage (DC)
- Structure and fault detection (Category)
- Tolerance to common-cause faults (CCF)
- Validation and documentation
- Analysis, calculation and testing of the safety function
- Verification that the PLr has been achieved
Widely used in combination with Safety PLCs, relays, Sensors and Actuators.
🏭 Application in industrial automation
- Machines with moving parts, conveyors, presses, packaging lines
- Control cabinets with integrated emergency stops, light curtains, door interlocks
- PLC control with safety functions
- Mechanical or electrical interlocks
- Guard detection, two-hand controls, speed monitoring
ISO 13849 sets requirements for the hardware, software, design and lifespan of safety components.
🔍 PL levels explained
| PL | Meaning | Application |
|---|---|---|
| a | Very low – basic safety | No risk of serious injury |
| b | Low | Light hazards |
| c | Medium | Moving parts, crushing hazards |
| d | High | Pressing machines, robots |
| e | Very high – critical | Presses, saws, fatal risks |
The PLr is the minimum required level per safety function, to be determined via a risk graph.
🔐 Safety considerations
- Safety PLC or safety relay with redundant circuits
- Lock-out Tag-out and work permit procedures support maintenance on PL provisions
- Fault detection and diagnostics (e.g. via test pulses)
- Integration of safety components with certified PPE
- Validation and periodic checks required (e.g. during risk inventory and evaluation or Audit)
Components must be CE-certified and suitable for use in PL applications.
📌 In summary
NEN-EN-ISO 13849 sets requirements for the design and performance characteristics of machine safety systems. The standard determines which measures are needed for machines to operate safely under both normal and faulty conditions.