EN ISO 13849-1 (Safety-Related Parts of Control Systems)
The standard covering the design and validation of safety-related parts of control systems. It classifies capability with a performance level scale from a to e, and architecture with Categories B, 1, 2, 3 and 4; architecture, component lifetime and diagnostic coverage all enter the calculation together.
The standard aims to express quantitatively how reliable a safety function is. The process works by first determining the required performance level through risk assessment, then calculating the level actually reached by the designed circuit.
Inputs to the calculation:
- Category: the architecture of the circuit, redundancy and tolerance to a single fault.
- MTTFd: the mean time to dangerous failure of the channel, in years.
- Diagnostic coverage: the proportion of dangerous failures that can be detected.
- Common cause failure: measures taken against the risk of redundant channels failing together.
For the machine stop function on a crane radio remote control, the target commonly used in the sector is Category 3 and performance level d; for the emergency stop function the general minimum expectation is cited as performance level c, and the risk assessment may require higher. These levels are not declared for AXI products; do not attribute a performance level to a product.
Context in which this term is used: Wireless remote control installation: pairing, relays, safety