The Siemens 3SK1111-1AB30 is a SIRIUS safety relay with three enabling circuits, designed for safety-related shutdown of machinery per IEC 61508 and IEC 62061, both rated SIL 3. It operates on a 24 VDC supply (rated value, with an operating range of 0.85 to 1.2 times nominal at DC). The relay contacts are rated 1 A at 24 V, 1.5 A at 115 V, and 1.5 A at 230 V — these are the switching currents per enabling path, not the total through-contact rating.
Safety architecture and SIL 3
The 3SK1111-1AB30 is a relay-based safety module, not a configurable controller. It provides three enabling paths (relay enabling circuits) that drop out on a safety demand. The SIL 3 rating per IEC 61508 and IEC 62061 means it meets the highest single-device integrity level for machinery safety — suitable for guarding applications where a single fault cannot lead to loss of the safety function. It also carries a start input and a feedback input, allowing monitored start and external contactor feedback for cross-monitoring.
The housing is 22.5 mm wide, 100 mm high, and 121.6 mm deep — a standard single-module footprint for DIN-rail safety relays. The terminal wiring accepts solid conductors 1x (20…14 AWG) and 2x (18…16 AWG), or stranded 1x (20…16 AWG) and 2x (20…16 AWG), with core-end processing for 1x (0.5…2.5 mm²) and 2x (0.5…1.0 mm²).
Shock resistance is 10 g for 11 ms. Total current through the device is limited to 12 A maximum, with a maximum power loss of 2 W. Response times: typical 65 ms, maximum 75 ms at DC; at AC maximum 320 ms. EMC compliance is to IEC 60947-5-1 and IEC 61000.