The Siemens 3SK1111-2AB30 is a SIRIUS safety relay designed for enabling circuits in safety-related applications. It's rated SIL 3 according to IEC 61508 and IEC 62061, which means it's suitable for safety functions up to that integrity level — think emergency stops, guard door monitoring, or two-hand control circuits where you need a certified fail-safe path. It has a start input and a feedback input, so you can wire it for monitored manual start or automatic restart depending on the risk assessment. The relay handles a total current maximum of 12 A and operates on a 24 V rated supply with a tolerance of 0.85 to 1.2 times nominal at DC.
At 22.5 mm wide and 100 mm tall, with a depth of 121.6 mm, this relay fits a standard DIN-rail enclosure. Fastening is by screw and snap-on mounting — so it clips onto the rail and can be screwed down for vibration resistance. Mounting position is any, which helps when you're packing a dense panel. Wire termination accepts solid or stranded conductors: 1x (20...16 AWG) or 2x (20...16 AWG). With core end processing (ferrules), it takes 1x (0.5...1.0 mm²) or 2x (0.5...1.0 mm²). That covers most control wiring in a standard panel.
EMC emitted interference complies with IEC 60947-5-1 and IEC 61000. Power loss is 2 W maximum, which is modest for a safety relay of this class. Typical response time is 65 ms, maximum 75 ms at DC; at AC the maximum is 320 ms. That 320 ms figure matters if you're calculating stop distances for a guard door — account for it in your safety distance formula.