The Siemens 3RT2636-1AK65 is a SIRIUS capacitor contactor, size S2, designed specifically for switching capacitor banks in power factor correction (PFC) applications. Unlike a standard motor contactor, this part is built to handle the high inrush currents and transient loads that capacitors present when they energize.
The switching capacity varies with the applied voltage: at 230 V AC it handles 6 A, at 400 V AC it handles 3 A, and at 690 V AC the rating drops to 0 A — meaning this contactor is not intended for 690 V capacitor banks. At 24 V it switches 6 A, at 60 V it switches 2 A, and at 110 V it switches 1 A. These are the AC switching ratings for the capacitor load type, not general-purpose or motor ratings. Maximum switching frequency is 100 operations per hour at 230 V, 240 V, and 400 V. At 480 V it drops to 60 ops/h, at 500 V to 55 ops/h, at 600 V to 40 ops/h, and at 690 V to 30 ops/h. These limits reflect the thermal stress of capacitor switching; exceeding them risks contact welding or premature wear. The contactor measures 65 mm wide, 114 mm high, and 130 mm deep — a size S2 footprint that fits standard 35 mm DIN rail per DIN EN 50022. That gives panel builders room to fit it into tight enclosures. Terminals accept solid conductors from 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². For stranded wire, the range is 2x (16 to 35 mm²) or 1x (16 to 50 mm²). The coil connection uses screw-type terminals.