The Siemens 3RT2636-1NB33 is a size S2 capacitor contactor rated AC-6b for 50 kVAr at 400 V, 3-pole, with a 20-33 V AC/DC coil. It includes an integrated varistor for surge suppression and comes with 1 NO + 1 NC auxiliary contacts, screw terminals.
What the AC-6b rating means for fit
AC-6b is the utilization category for switching capacitor banks. The integrated varistor suppresses switching transients that capacitor banks generate on make and break.
Coil and control voltage
The 20-33 V AC/DC coil accepts both AC and DC control signals across that voltage window, 50/60 Hz. This wide-range coil simplifies panel wiring — one part number covers 24 V nominal control circuits with tolerance for line drop.
Panel integration
Size S2 mounts on DIN rail in the standard SIRIUS footprint. Screw terminals accept up to the wire gauge typical for 50 kVAr capacitor switching. The 1 NO + 1 NC auxiliary contacts are built in, so no separate aux block is needed for basic feedback or status.