Emergency stop shutdown to SIL 3 or PL e with fail-safe motor starters and a 3SK2 safety relay
The safety relay monitors the emergency stop command device. When the emergency stop command device is actuated, the safety relay switches the fail-safe motor starters off via the device connectors.
The motor starters then safely shut down the load. If the emergency stop command device is unlocked, the Start button can be used to switch on again.
In this example, it is assumed that the hazard emanates from only one of the drives in each case, but that an emergency stop switches off a group of drives. For this reason, only a single motor starter is considered in the safety evaluation, and this is used as an example.
If the hazard emanates from the movement of several drives, all motor starters involved with this hazard must be taken into account in the safety Evaluation.