Risk Reduction; A.3.2.8 Risk Reduction - Siemens SINAMICS G120 Function Manual

Figure A-17
Risks must be reduced by designing and implementing the machine accordingly (e.g. by
means of controllers or protective measures suitable for the safety-related functions).
If the protective measures involve the use of interlocking or control functions, these must be
designed according to EN ISO 13849-1. For electrical and electronic controllers, EN 62061
can be used as an alternative to EN ISO 13849-1. Electronic controllers and bus systems
must also comply with IEC 61508.
A.3.2.8

Risk reduction

Risk reduction measures for a machine can be implemented by means of safety-related
control functions in addition to structural measures. To implement these control functions,
special requirements must be taken into account, graded according to the magnitude of the
risk. These are described in EN ISO 13849-1 or, in the case of electrical controllers
(particularly programmable electronics), in EN 61508 or EN 62061. The requirements
regarding safety-related controller components are graded according to the magnitude of the
risk and the level to which the risk needs to be reduced.
EN ISO 13849-1 defines a risk flow chart that instead of categories results in hierarchically
graduated Performance Levels (PL).
IEC/EN 62061 uses "Safety Integrity Level" (SIL) for classification purposes. This is a
quantified measure of the safety-related performance of a controller. The required SIL is also
determined in accordance with the risk assessment principle according to ISO 12100 (EN
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
Function Manual, 04/2014, FW V4.7, A5E34261271B AA
Iterative process for achieving safety
A.3 Standards and specifications
Appendix
327