Functional safety
13.4 Fundamental safety technology principles
SINAMICS DCM DC Converter
Operating Instructions, 12/2018, A5E34763375A
713
The Safe Stop 1 function (SS1-t) function means that the motor is stopped and then the
torque-generating energy is shut down (STO). When SS1-t is activated, the inverter brakes
the motor along a braking ramp. This happens via the braking function integrated in the drive
along the OFF3 ramp.
SS1-t corresponds to the SS1-t function according to EN 61800-5-2.
SS1-t can be used wherever the load torque cannot stop the motor in a sufficiently short time
as a result of friction – or where there is a safety risk if the drive coasts down (STO).
Safety functions of the SINAMICS DC MASTER
Technical fundamentals and data
The SINAMICS DCM is equipped from function version 04 with a safety-related switch-off
signal path for STO. An additional license is not required for this function.
In connection with an external safety relay (e.g. 3SK1) and with a redundant switch-off signal
path via armature line contactor, a Safe Torque Off (STO) or Safe Stop 1 (SS1) safety
function SIL 3/PL e Cat. 4-capable application is achieved according to EN 62061 or
ISO 13849-1.
The STO safety function comprises three safety element functions:
1.
P
erformed externally, e.g. by emergency stop button or other sensors
2.
P
erformed externally, e.g. by a 3SK1 safety relay
– Evaluation and diagnostics of the input / sensor circuits
– Logical interconnection of input signals as well as diagnostics and parameterization
– Controlling the switch-off signal paths
– Diagnostics of the switch-off signal paths via their feedback circuits
3.
P
erformed by two separate channels with different technologies:
– Switch-off signal path channel 1 through the armature line contactor
– Switch-off signal path channel 2 through the STO switch-off signal path of the DCM
The structure from the two switch-off signal paths incl. their diagnostic paths fulfill a SIL 3
or PL e Cat. 3 / 4-capable STO shutdown.
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