Schmersal SRB 301ST-24V Safety Relay Module

Schmersal SRB301ST-24V is a compact safety-relay module designed for dual-channel safety control in industrial automation. It provides two independent safety contacts (S11-S12 and S21-S22) plus a single auxiliary/status contact, enabling both dual-channel safety monitoring and signaling feedback. The device accepts a universal 24 V coil (24 VAC or 24 VDC) with automatic restart options via a reset- or start-button, and an optional bridge for configurations where feedback isn’t required. Housed in IP20 protection with removable terminals, the unit measures 22.5 x 121 x 120 mm, making wiring and mounting straightforward in control panels. The SRB301ST-24V complies with safety standards including ISO 13849-1 and IEC 61508, with EN 81-20/50 referenced in the accompanying documentation, and offers a PFH rating up to 2.0 × 10^-8 per hour depending on configuration. Common applications include integration with safety devices such as emergency stops, safety light curtains, and interlocks in conveyors and machine tools, where either single-channel operation (via bridging) or true dual-channel monitoring is required for enhanced safety performance.