The Siemens 3RT1926-1BD00 is a SIRIUS varistor-type surge suppressor designed to clamp voltage transients across the coil of Size S0 through S3 contactors. It accepts a control supply voltage of 127...240 V AC at 50/60 Hz or 150...250 V DC, making it suitable for panels where the same contactor accessory must work across both AC and DC control circuits without swapping modules.
Lifecycle and replacement path
This part is marked as a phased-out product. The official successor is the SIRIUS 3RT2 series surge suppressor, which is the drop-in replacement for new builds and panel revisions. For existing panels already wired with the 3RT1926-1BD00, the 3RT2 variant shares the same Size S0...S3 mounting footprint and voltage range, so a BOM swap should not require re-routing the control wiring.
What the voltage ratings mean for fit
The 150...250 V DC range matches the typical DC bus voltage in 24 VDC systems with a boost converter or in 220 VDC railway/marine control circuits. Because the suppressor uses a varistor (metal-oxide), it clamps the peak voltage rather than rectifying or filtering — so the AC and DC ranges are separate operating windows, not a single universal band. Verify your control supply voltage falls within one of the two stated ranges before fitting.
The suppressor mounts directly onto the contactor coil terminals — no DIN-rail space consumed. It fits SIRIUS contactor frames Size S0, S1, S2, and S3. In a typical panel, the varistor sits between the A1 and A2 coil terminals; the contactor's own snap-on slot holds it in place. No additional wiring is needed beyond the existing coil circuit.