Schmersal – SRB‑E‑301ST – Configurable Safety Relay 24 V AC/DC, 3NO + 1NC

The Schmersal SRB‑E‑301ST is a multifunctional configurable safety relay designed for emergency-stop, guard-door, light curtain, and safety mat applications. With selectable 1‑ or 2‑channel input logic, auto‑start/monitored‑start options, and three safety (NO) plus one monitoring (NC) contact, it meets EN ISO 13849 PL e and SIL 3 safety standards. This compact 22.5 mm DIN‑rail module supports 24 VAC/DC control voltage and includes configurable wiring modes via dual-channel DIP switches.

Key Features & Technical Specifications:

• Model / P/N: SRB‑E‑301ST (Schmersal 103007672)  

• Control Voltage: 24 VAC/DC ± tolerances; ≤2.4 W/7 VA power consumption

• Safety Contacts: 3 × NO safety outputs (stop category 0); 1 × NC monitoring output (auxiliary)  

• Input Logic: Configurable 1- or 2-channel input; auto-start or monitored-start via DIP switches; short/open circuit detection and earth-fault monitoring  

• Safety Rating: SIL 3 per IEC 61508; PL e, Category 4 per EN ISO 13849‑1; PFH ≤ 1.25×10⁻⁸/h  

• Switching Ratings: AC-15 230 VAC, 4 A; DC-13 24 VDC, 4 A; auxiliary contact: 24 VDC @ 1 A  

• Response Times: Pull-in ≤ 150 ms; drop-out ≤ 10 ms (power-fail/emergency)  

• Mounting & Dimensions: DIN-rail EN 60715; 22.5 mm wide; 175 g; operating –25…+60 °C; IP40 enclosure / IP20 terminals  

• EMC & Insulation: Rated impulse withstand 4 kV, pollution degree 2, overvoltage category III; EMC compliant  

• Indicators: LEDs for status and fault display, plus removable plug-in screw terminals