Troubleshooting of Siemens SIRIUS 3SK2 Safety Relay

7.3 Functional testing requirements after replacement

According to the EU Machinery Directive and functional safety standards, after each component replacement, the following must be carried out:

Configuration testing: Verify that the downloaded configuration in Safety ES is consistent with the target.

System testing: Trigger each safety sensor (emergency stop, protective door, etc.) to confirm that the actuator is correctly turned off; Reset and start again, confirm that the recovery logic is correct.

For electromechanical actuators (such as 3SK1 output extensions and contactors), the functional testing intervals must comply with:

SILCL 2 or PL d: ≤ 1 year

SILCL 3 or PL e: ≤ 1 month

Common faults and countermeasures in typical application scenarios

8.1 Emergency stop circuit (dual channel NCNC, cross circuit detection activated)

Phenomenon: After pressing the emergency stop button, it cannot be turned off or reset, and the SF red light remains on.

Diagnosis: Check the diagnostic display screen and it will prompt 'Cross circuit at input n'. The usual reason is that the wiring of two channels is short circuited externally, or one of the contacts is stuck.

Solution: Check if the two NC contacts of the emergency stop button are independently wired and measure their continuity. After repairing, press RESET to confirm.

8.2 Protective door monitoring (electronic RFID safety switch)

Phenomenon: Unable to power on after closing the protective door, SF flashes red (self confirmation).

Diagnosis: Logical error, infinite time difference but sequence violation. Perhaps the feedback signal from the door lock did not change within the allowed time.

Solution: Check the timing of the locking feedback contacts (such as Lock engaged) and door position contacts of the safety switch. The difference time can be set to a finite value (such as 1 second) in Safety ES to quickly capture timing errors.

8.3 Two handed operation (Type IIIc)

Phenomenon: After pressing two buttons, the machine does not start and the SF red flashes.

Diagnosis: The synchronization time exceeds 0.5 seconds, or the crossover circuit detects abnormal signals in two channels.

Solution: Check if both buttons are pressed simultaneously (difference<500ms). If the wiring is long, shielded cables can be considered. For NONO type inputs, cross circuit detection must be activated.

8.4 3SK1 output extension controlled through device connector does not operate

Phenomenon: F-Q3-C in 3SK2 logic has output 1, but the relay for 3SK1 extension is not engaged.

Diagnosis: First, check if the position of the slide switch on 3SK1 matches the parameterized output in Safety ES ("UnderELAYED" corresponds to F-Q3-C, "DELAYED" corresponds to F-Q4-C). Secondly, confirm whether the expansion module is powered through the 3ZY12 device connector and not connected to an external power source on A1/A2 (otherwise it will bypass the safety function).

Solution: Adjust the slider switch or modify parameterization to remove external wiring on A1/A2.

Daily maintenance and preventive diagnostic recommendations

Regular optimization of dark test parameters: If there is a capacitive load (such as LED indicator lights or long cables) connected to the output terminal, the maximum readback time (3-400 ms) should be increased according to the "capacitive load curve" to avoid erroneous shutdown caused by dark test pulses.

Monitoring environmental temperature: The 22.5mm model can be installed independently with a maximum temperature of 60 ° C; it may be downgraded to 40 ° C when configured with DP interfaces or expansion modules. If the cabinet temperature exceeds the limit, the signal loop connector (3ZY1212-2AB00) needs to be used to increase the heat dissipation distance.

Establish diagnostic logs: Regularly read device logs (Logbook) through Safety ES, record timestamp fault information, and use it for predictive maintenance.

Firmware and GSD file updates: Visit Siemens Industrial Online Support to obtain the latest version to fix known issues.