Siemens 3TH20-22-0BB4 Control Relay 24V DC Coil

Siemens 3TH20-22-0BB4 is a four-pole auxiliary contactor (control relay) with a 24 V DC coil, designed to interface control logic with higher‑power circuits. It provides two normally open and two normally closed auxiliary contacts (2NO+2NC, 22E) and uses screw-terminal connections for reliable field wiring; the front is IP20 rated. The device is specified for DC operation at 24 V and, in AC‑15 service, supports up to 4 A at 230 V and 3 A at 400 V, making it suitable for signaling and interlocking tasks rather than power switching. Typical applications include pilot control, interlocks, and expanding control circuits in Siemens automation systems, often used in conjunction with main contactors in the 3TH20 family.