Functional Safety - Siemens SINAMICS S120 Function Manual

Standards and regulations
10.1 General information
10.1.2

Functional safety

Safety, from the perspective of the object to be protected, cannot be split-up. The causes of
hazards and, in turn, the technical measures to avoid them can vary significantly. This is why
a differentiation is made between different types of safety (e.g. by specifying the cause of
possible hazards). "Functional safety" is involved if safety depends on the correct function.
To ensure the functional safety of a machine or plant, the safety-related parts of the
protection and control devices must function correctly. In addition, the systems must behave
in such a way that either the plant remains in a safe state or it is brought into a safe state if a
fault occurs. In this case, it is necessary to use specially qualified technology that fulfills the
requirements described in the associated Standards. The requirements to implement
functional safety are based on the following basic goals:
● Avoiding systematic faults
● Controlling random faults or failures
Benchmarks for establishing whether or not a sufficient level of functional safety has been
achieved include the probability of hazardous failures, the fault tolerance, and the quality that
is to be ensured by avoiding systematic faults. This is expressed in the standards using
specific classification. In IEC/EN 61508, IEC/EN 62061 "Safety Integrity Level" (SIL) and
EN ISO 13849-1 "Category" and "Performance Level" (PL).
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Function Manual, 12/2018, 6SL3097-5AR00-0BP1
Safety Integrated