OverviewSafety categoriesSafety categories according to EN 954-1| Category | Summary of the requirements | System behaviour | Principle | | B | The controls must be so designed that they can withstand the expected influences | A fault can lead to the loss of a safety function | Mainly characterised by the selection of components | | 1 | The requirements of B must be fulfilled; use of tried and tested safety components and principles | As for B, but with higher safety-related reliability | | 2 | The requirements of 1 must be fulfilled; additional testing of the safety function at suitable intervals | A fault is recognised at the next check | Mainly characterised by the structure of the controls | | 3 | The requirements of 1 must be fulfilled; a single fault must not lead to the loss of the safety function | When a single fault occurs, the safety function remains intact | | 4 | The requirements of 3 must be fulfilled; the single fault must be recognised before or at the next demand on the safety function | When faults occur the safety function remains intact. The faults are recognised |
Choosing safety categoriesChoosing safety categories according EN 954-1 | S - Severity of the injury | F - Frequency and duration | P - Possibility of avoiding the hazard | | S1 - slight injury | F1 - seldom to often and/or short duration | P1 - possible under certain conditions | | S2 - severe irreversible injury
to one or more persons
or the death of a person | F2 - often to continuously and/or long duration | P2 - scarcely possible |
Stop categories according to EN 60204Stop category 0:Shutdown by immediately switching off the energy supply to the machine drives (uncontrolled shutdown).Stop category 1:Controlled shutdown, whereby the energy to the machine drives is only switched off when the machine has come to a standstillStop category 2:Controlled shutdown, where the energy supply is still fed to the machine drives (not permitted for Emergency Stop function)TÜV and BIAAcknowledgement by TÜV and BIAThe concept of Safety at Work was acknowledged by the German TÜV (Technischer Überwachungsverein) and BIA (Berufsgenossenschaftliches Institut für Arbeitssicherheit). Useful Links | 
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