Moeller – ESR4-NO-21 – Safety Relay 24 V DC, 3 NO + 1 NC Outputs, Dual-Channel

The Moeller ESR4-NO-21 is a dual-channel safety relay used for monitoring emergency stop buttons, guard doors, and safety interlock circuits. It operates on 24 V DC and provides three safety contacts plus one auxiliary status output. The relay features cross-fault monitoring, redundant circuit design, and selectable automatic or manual reset modes — ideal for machinery safety control systems.