The Siemens SIRIUS 3RT1936-1TS00 is a DC surge suppressor with diode assemblies, designed to plug into the bottom of S2 and S3 contactor sizes. It handles control supply voltages from 30 to 250 V DC, suppressing inductive kickback from the contactor coil on DC control circuits — a common requirement on panels with 24 V, 48 V, 110 V or 220 V DC control buses.
This part is marked as a phased-out product. Siemens lists the official successor as the SIRIUS 3RT2936-1ES00, which is the preferred replacement.
What the DC Voltage Range Means
The 30 to 250 V DC range covers the standard DC control voltages found across industrial panels — 24 V is below the floor, so this suppressor won't activate on a 24 VDC coil circuit. It's sized for 48 V, 110 V, 125 V, and 220 V DC control buses where the diode assembly clips the voltage spike when the coil de-energizes, protecting the PLC output or relay contact that drives it.
Panel Integration
The suppressor plugs into the bottom of S2 or S3 contactors — no wiring needed beyond seating it onto the contactor's coil terminals. It occupies no additional DIN-rail space, which matters when the panel is already dense. The diode assembly is polarity-sensitive; verify the DC supply orientation before seating the module.