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Protection Level (PL)

The Protection Level (PL) of a machine is the level of safety to which the safety related functions are required and available. Harmonised standard IN ISO 13849-1:2009, replaces EN 954-1/1A and the old category of safety, using a hierarchial series of protection levels in an ascending order thus;

PL a-Lowest functional safety level

PL b

PL c

PL d

PL e Highest functional safety level.