Emergency Stop
What is the minimum Performance Level (PL) for an E-Stop per ISO 13850?
PL c, achievable via Category 1, 2, or 3 architectures.
Can an E-Stop impair release of trapped persons?
No; ISO 13850 explicitly prohibits affecting functions intended for releasing trapped individuals.
Is an E-Stop a safety device?
No; it is a safety function, not part of SRP/CS, and must not substitute for dedicated protective devices.
An Emergency Stop (E-Stop) is a safety function initiated by a single human action to avert arising or reduce existing hazards to persons, machinery, or work in progress. It must override all other control functions and prevent machine restart until manually reset, typically using robust, accessible devices like red mushroom-head buttons.
On the shop floor, E-Stops are installed as robust, accessible devices (e.g., red mushroom-head buttons) at operator stations, exit locations, and intervention points. When activated, they cut power to prime movers via Category 0 or 1 stops, locking the system until manually reset. They serve as complementary backup measures, not primary safeguarding, and must be integrated with risk assessments to ensure proper placement and reliability, often requiring a minimum Performance Level of PL c per ISO 13850.
Using E-Stops as primary safeguarding instead of guards or interlocks, violating ISO 13850 which mandates they are complementary backup measures.
Installing E-Stops with insufficient reliability below PL c or SIL 1, such as using non-diagnostics Category 1 architectures in high-risk scenarios.
Over-reliance on E-Stops for non-safety issues like clearing jams or maintenance setup, leading to delayed production and potential safety degradation from frequent misuse.