Allen-Bradley 440R-S23174 GuardMaster CU4 Safety Relay

The Allen-Bradley GuardMaster CU4 Safety Relay, model 440R-S23174, is a compact two‑channel safety relay designed to guard industrial machinery. It accepts a 24 V AC/DC input and provides delayed safety outputs with a timing range of 0.5 to 10 seconds for this CU4 variant, making it suitable for controlled restart and safe‑stop sequencing after guard conditions are satisfied. Housed in a 22.5 mm‑wide enclosure, it is DIN‑rail mountable and supports Auto/Manual reset configurations to suit different safety strategies in the field. This CU4 unit integrates with GuardMaster safety sensors and interlocks to deliver a monitored safety circuit, enabling reliable verification of dual safety devices within a single housing—an essential capability for safeguarding conveyors, presses, and packaging lines. As part of the GuardMaster family, the 440R‑S23174 is intended for applications requiring two safety channels with a built‑in delay to ensure proper hazard mitigation and deterministic restart behavior after safety conditions are cleared. Its timing granularity and compact form factor help streamline wiring and panel real estate while preserving the integrity of safety logic across multiple devices in automation environments.