Siemens 3TK2840-1BB40 Relay

Siemens 3TK2840-1BB40 is a SIRIUS safety relay with an electronic release circuit (RC) designed for 24 V DC control networks, in a compact 22.5 mm-wide brick that mounts on a DIN rail and uses screw-terminal connections. This single-channel device provides two safety contacts for monitoring safety switches and interlocks, with an instantaneous RC release and no delayed-time option, and it supports autostart/monitored start modes as a basic safety unit. It is rated for performance up to SIL 2 and PL d, offering robust fail-safe behavior in industrial safety circuits, and is specified for operation from -25 to +60 °C (storage -40 to +80 °C) with a maximum installation altitude of 2,000 m. Housing protection is IP40 and terminal protection is IP20, aligning with typical industrial enclosure requirements. Applications include safety gate interlocks, emergency-stop circuits, and other safety-controller configurations where reliable, dual-contact monitoring and a compact form factor are essential.