Siemens 3SK1111-1AB30 Safety Relay 3NO 1NC 24V AC DC

Siemens 3SK1111-1AB30 safety relay is a DIN-rail mounted device that guards industrial safety circuits by monitoring emergency-stop devices, safety gates, and light curtains, delivering three normally open (NO) contacts and one normally closed (NC) auxiliary contact to ensure safe shutdown and protection of personnel and equipment. This unit, part of the SIRIUS 3SK1 Standard series, operates from 24 V AC/DC and is suitable for use in machinery safety systems across manufacturing, robotics, packaging, and automated equipment where reliable fault detection and compliance with safety standards up to Category 4 (EN ISO 13849-1) are required. Key specifications include IP20 protection, dimensions approximately 22.5 × 100 × 121.6 mm, operating temperature range −25°C to +60°C, and screw-terminal connections for DIN rail installation. The 3NO/1NC configuration supports monitoring of safety circuits while providing a fail-safe path for controlled shutdown, and it is commonly used for replacement or retrofit in existing safety control architectures. Common replacements include Siemens 3SK1111-2AB30, 3SK1121-1CB41, and 3TK2821-1CB30.