The Siemens SIRIUS 3RT2916-1LP00 is a surge suppressor built around a suppression diode with an integrated LED indicator, rated for 150-250 V DC control circuits. It clips directly onto S00-size contactors in the 3RT2.1 series and auxiliary contactors in the 3RH2 series — no additional wiring or panel space needed beyond the contactor's own footprint.
The 150-250 V DC range covers the standard DC control voltages used across European and North American panel designs — 125 V DC, 220 V DC, and 250 V DC coils all fall inside this window. The diode design means the suppressor clamps the flyback voltage from the contactor coil when it de-energizes, protecting nearby PLC outputs and DC supplies from voltage spikes. The LED gives a quick visual check that the suppressor is live and the coil circuit is energized — useful during commissioning or fault-finding without reaching for a meter. Because it's a diode-type suppressor, polarity matters: the DC supply must be connected with the correct polarity relative to the coil. Swap the leads and the diode blocks rather than suppresses. The clip-on mounting and S00 size mean it snaps onto the contactor's front without tools, and the 9 mm depth keeps the assembly within the contactor's own envelope — no extra clearance needed in the panel.
The 28 mm width and 46 mm height match the contactor's own dimensions, so it doesn't crowd neighboring components on the DIN rail.