Capacitor switching — what the ratings mean
The Siemens 3RT2628-1AK65 is a dedicated capacitor contactor from the SIRIUS family, Size S0. It's built for switching power-factor-correction capacitor banks, not general motor loads — the switching capacity figures reflect inrush-limited capacitor duty: 6 A at 230 V, 3 A at 400 V, 1 A at 690 V. That 6 A at 230 V is the headline number for a typical 230 V bank; at 400 V you're down to 3 A, so size up if the bank draws more. The coil is 110-120 VAC, 50/60 Hz, screw-type terminals.
Switching frequency limits matter here
Capacitor contactors see repeated switching — power factor correction cycles with load changes. The 3RT2628-1AK65 is rated for 100 switching operations per hour at 230-400 V, dropping to 70/h at 480 V, 45/h at 600 V, and 36/h at 690 V. If your application cycles faster than that, you need a larger contactor or a different switching topology.
DIN rail fit and wiring
Size S0 gives you a 45 mm wide, 150 mm tall, 155 mm deep footprint. That helps when the gland plate or busbars force an odd orientation.