The Siemens 3SK1122-2CB42 is a SIRIUS safety relay with solid-state enabling circuits, rated for 24 V DC control supply. It carries SIL 3 per IEC 61508 and PL e per ISO 13849-1, with a safe failure fraction of 99% — meaning it meets the highest integrity level for guarding applications where a single fault cannot cause loss of the safety function.
Spring-loaded push-in terminals accept solid wire 1x (20…16 AWG) or stranded 1x (20…16 AWG), and with a ferrule 1x (0.5…1.0 mm²). The 121.6 mm depth means it projects about 5 inches from the rail — account for that when planning gland-plate clearance on a shallow enclosure.
Safety architecture and inputs
This relay provides two instantaneous safety contacts and two delayed switching outputs. It accepts a start input, a safety switch input, and a feedback input.
Degree of pollution 3 and overvoltage category 3 suit industrial control panels without climate control. Shock resistance is 10 g / 11 ms. EMC emitted interference meets IEC 60947-5-1, Class A (industrial environment). The lifecycle status is current — this is an active catalog item, not a phase-out or NRND line.