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1 article tagged “pfhd”.

IEC 62061 PFHd calculation block diagram showing sensor, logic solver and actuator with probability of dangerous failure per hour values
functional safetyiec 62061pfhd

IEC 62061 PFHd Calculation: A Step-by-Step Guide

PFHd is the number that decides whether your safety function hits SIL 2. Here is how to calculate it correctly under IEC 62061, with a real worked example.

Jun 27, 2026 · 8 min read

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