Schmersal SRB 301LC-24V Safety Relay

Schmersal SRB301LC-24V is a three-safety-contact safety relay module that processes non-potential-free safety contacts and provides a dedicated signaling output for safety circuits. It is designed for use in machine safety systems to monitor devices such as emergency-stop buttons, guard systems, and pull-wire emergency stop switches. The unit operates from a 24 V DC control supply and features three safety contacts plus one signaling/auxiliary output; input currents are typically around 0.1 A with digital inputs showing a conduction resistance up to 40 Ω, and the auxiliary contact switches up to 2 A at 24 V DC. The module is 22.5 mm wide and rated IP40 for protection against dust and incidental contact; it also supports automatic reset (auto-reset) and is designed to detect cross-short, cable breaks, and earth-leakages in the monitoring circuit. For configuration, it shows wiring options such as bridging S11/S12 and S21/S22 for automatic start in certain setups, and uses standard X1/X2 feedback connections in multi-channel arrangements. Typical applications include guarding doors and interlocks, emergency-stop systems, and cross-wire monitoring of safety circuits to maintain safe operation.