The Siemens 3SK1213-1AJ20 is a SIRIUS safety relay output expansion module — it adds relay enabling circuits to an existing safety relay setup, not a standalone safety controller. The screw terminals accept 1x (20…12 AWG) or 2x (20…14 AWG) solid wire, so it handles the typical field wiring gauge for safety circuits without needing ferrules on the solid runs. Mounts on horizontal standard DIN rail via screw and snap-on fastening — no tools needed for the snap, but the screw secures it against vibration in high-shock environments (rated 5 g / 10 ms). Depth is 121.6 mm, width 90 mm, height 100 mm; that footprint leaves room for a terminal block row above or below in a standard 600 mm enclosure.
The 10 A rating holds across 24 V, 115 V, and 230 V — that's the contact rating, not the coil draw. The coil itself is rated 115 V at 50/60 Hz with an operating range of 0.85…1.1 times rated voltage, so it picks up reliably even on a sagging line. Switching frequency maxes at 360 operations per hour, which is fine for machine-guarding cycles but not for high-speed sorting gates. Total current through the module is capped at 30 A, so sum the loads across all expansion contacts. EMC compliance to IEC 60947-5-1 and IEC 61000 means it won't radiate noise that upsets nearby sensors or PLC inputs.
Approvals and documentation
UL approval is on record — that clears it for North American panels without a separate evaluation. The SIRIUS family carries CE marking as standard. For compliance files, the manufacturer provides RoHS and REACH declarations along with the IEC test reports referenced in the EMC standards.