Introduction
1.6 Field circuit description
Application document for functional safety STO, SS1 (ISO 13849-1)
Compact User Manual, 09/2016, A5E34871844AM
15
Via the expansion device, independent of the SINAMICS DCM state, a safety-related
coupling relay is switched, which immediately opens the circuit breaker with the undervoltage
coil - or for a power contactor, disconnects the solenoid.
If STO is not selected, then the circuit breakers or power contactors are switched with a
positively-driven interface relay from the SINAMICS DCM.
Two switching devices are required to achieve SIL2 according to EN62061 and PL d
according to DIN EN ISO 13849-1.
If a power contactor is used in the field circuit, then this can be optionally switched with the
safety function. If the field contactor is to be integrated in the safety function, then the field
contactor must be opened and closed with the output expansion of the safety relay using a
safety-related interface relay. The positively-driven NC contact of the coupling relay - as well
as the mirror contact of the field contactor - must be integrated in the feedback circuit of the
safety relay. This version is shown in the circuit examples.
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