What does an EN ISO 13849-1 performance level mean in hydraulic control?
EN ISO 13849-1 provides the method for determining and validating the performance level (PL) for safety-related parts of a control system; it applies to all technologies: electrical, hydraulic, pneumatic, and mechanical. ISO 13850 requires at least PLr c for the emergency stop function, and PLr d or e is expected where the risk assessment requires it. PL is a machine property, not the label of a single component.
PL is a scale expressing how reliable a safety function is against failure. The important point is this: PL is defined per function, not per product. The statement "this remote control is PL d" is technically incomplete; what is assessed is an entire chain such as the "emergency stop function" or the "stop the lifting motion function": detection, logic processing, and output.
The reason it matters specifically for hydraulics is that the standard covers not just electronics but hydraulic and mechanical components as well. The chain that stops a motion also includes the valve, the piping, and the cylinder.
For context: ISO 13850 requires at least PLr c for the emergency stop function; PLr d or e is expected where the risk assessment requires it. In Category 2 architecture, fault detection is provided only by checks carried out during operation at suitable intervals.
This information is given as a general engineering framework. The PL level a machine will reach is determined by that machine's own risk assessment and by evaluating all components in the chain together.
Full coverage of this topic: What Does the HCT402 Achieve, How, and How Much? A Technical Review