The Sirius 3RQ2 series of coupling relays from Siemens have mounting depths of 3.5 inches and provide from 24 to 240 V AC/DC. The relays are available with one, two, or three changeover contacts. These relays replace the 3RS18 series but with fewer variants due to a wide-range inputs. Using the same terminal assignment and minimizing the variant options make changeover to the new series fast and simple. The relays are designed for use with Simatic S7 controllers and Sirius contactors. Typical applications include galvanic isolation, signal amplification, and voltage conversion, for instance from 24 V DC to 230 V AC, as well as overvoltage and EMC protection for control systems. The relays feature hard gold-plated contacts for switching currents in the lower milliampere ranges and are particularly suited for PLC inputs and outputs. They come in high-grade industrial enclosure with user-friendly connections that simplify handling, installation, servicing, and wiring. Connections are made to large terminal cross-section of up to four square millimeters. Terminal covers are labeled to simplify wiring, and a DataMatrix code enables easy access to services and support. The relays meet CE, UL/CSA and EAC standards.