PL

Performance Level (PL) is a discrete level used in ISO 13849-1 to specify the safety-related performance of safety functions, ranging from PL a (lowest risk reduction) to PL e (highest risk reduction).

PL is determined through risk assessment and the structural and probabilistic properties of the safety function (category, MTTF_d, DC, CCF). A safety function's achieved PL must meet or exceed the required PL (PLr) determined by the risk estimation.