2 NC auxiliary switch for 3RT1 contactors
The Siemens 3RH1921-2EE02 is a lateral auxiliary switch block designed to snap onto the side of 3RT1 contactors, adding two normally-closed (NC) contacts. The contacts are encapsulated and rated as solid-state compatible, meaning they switch reliably at the low voltages and currents typical of PLC inputs and electronic control circuits. This rating confirms the switch will close consistently on dry logic-level signals without adding a sealing current resistor.
Switching capacity across control voltages
The 3 A / 110 V figure covers most 110 VAC control relay and contactor coil loads; the 0.3 A at 24 V is sufficient for a bank of PLC digital inputs or a small indicator lamp string. Mechanical service life is 10 million switching cycles typical, with surge voltage resistance rated at 6 kV and insulation voltage at 500 V for pollution degree 3. The IP20 front protection means the switch is touch-safe on the front face but not sealed against dust ingress into the enclosure.
Snap-on mounting and spring termination
The switch snaps onto the contactor without tools — the fastening method is snap-on mounting, and the 10 mm width means it adds minimal DIN rail space to the contactor assembly. The 71 mm depth and 72.5 mm height match the 3RT1 contactor envelope, so the assembled pair fits standard control panel cutouts and enclosure depths without interference.