Siemens AG 3RT1916-2FK21 Auxiliary Switch Block

Siemens Sirius 3RT1916-2FK21 is a solid-state, time-delayed auxiliary switch block that snaps to the front of Size S00 contactors to extend control logic without extra wiring. It provides one normally open (NO) and one normally closed (NC) output and features an OFF-delay timer adjustable from 0.5 to 10 seconds. The block operates on 100–127 V AC/DC and includes an integrated varistor for transient suppression. Designed for front-mounting on compatible Sirius Classic contactors, it enables time-based sequencing, interlocks, or signaling in motor-control and automation circuits by delivering a controlled delay after actuation. The accessory is compatible with Siemens 3RT1x contactors and completes the standard auxiliary circuit with a compact, front-mounted form factor.