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Entry type: Application example Entry ID: 109769503, Entry date: 09/05/2019

Emergency stop group shutdown up to SIL 3 or PL e via 3SK2 safety relay with PROFINET connection and fail-safe motor starters

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To be able to safely shut down a machine in an emergency, an emergency stop command device is attached and monitored by a 3SK2 safety relay. The safe group shutdown of the 3RM1 fail-safe motor starter is performed locally via device connectors via the safety relay. The higher-level controller functionally switches the motor starters via PROFINET.

Emergency stop group shutdown up to SIL 3 or PL e via 3SK2 safety relay with PROFINET connection and fail-safe motor starters

Operating principle

The 3SK2 safety relay monitors the emergency stop command device. When the emergency stop command device is activated, the safety relay shuts down the fail-safe motor starters via the device connectors. The motor starters then safely disconnect the load. If the emergency stop command device is unlocked, the start button can be used to switch on again.

The controller is connected with the safety relay via the PROFINET interface module. The operational switching of the motor starter is implemented in the user program of the controller and transferred to the 3SK2 via PROFINET. The 3SK2 forwards these control signals via its outputs (F-DQ or QM) to the control inputs of the motor starters (IN1 for direct on-line starters or IN1 and IN2 for reversing starters).

The feedback message regarding the current status of the safety function is sent from 3SK2 to the controller via PROFINET. It is also possible to read in the start button for re-activation via input modules of the controller instead of directly on the 3SK2 and to also transfer the signal to the safety relay via PROFINET.

In addition, a remote reset of the motor starters can be initiated by the controller via the PROFINET interface module in order to clear an error from one or more motor starters. The motor starters are shut down via the device connectors and then switched on again. In this way, group errors of the 3RM1 can be easily acknowledged without having to push the reset button on the device. The shutdown signal must be active for longer than 1 second. Please note that only group errors can be acknowledged. Device faults or a tripping of the motor or relay require acknowledgement via the reset button on the device. For more information, refer to the 3RM1 Equipment Manual  66295730 


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 multiple drives, all motor starters involved with this hazard must be taken into account in the safety evaluation.

 Registrierung notwendig  Safety-ES_Emergency_stop_SIL3_3SK2PN_group.zip (2,7 KB)

 Registrierung notwendig  SET_Emergency_stop_SIL3_3SK2PN_group_en.zip (8,5 KB) 

 Registrierung notwendig  TIA_Portal_Emergency_stop_SIL3_3SK2PN_group.zip (457,8 KB)

 Registrierung notwendig  Wiring_Emergency_stop_SIL3_3SK2PN_group.zip (103,9 KB)