The Siemens 3RT7916-1BD00 is a varistor-type surge suppressor designed to plug directly onto 3RT7 S00 frame contactors. It clamps voltage transients from the coil circuit, protecting nearby electronics and extending contact life on inductive loads.
Snaps onto the coil terminals of any 3RT7 S00 contactor — no wiring or additional mounting hardware needed. The varistor sits inside the contactor's terminal profile, so it does not increase the DIN-rail footprint of the contactor assembly.