Capacitor switching — what the ratings mean
The 3RT2645-1AP05: This is a SIRIUS capacitor contactor, not a general-purpose one. The maximum switching frequency falls off sharply as voltage rises: 200 operations per hour at 230 V, 100 at 400 V, and only 40 at 690 V. This derating is driven by the thermal recovery time of the arc chamber after a capacitive break — pushing the rate above the curve shortens contact life. Opening time is 10-21 ms with an arcing time of 10-20 ms. For power factor correction panels, this means the contactor clears before the upstream fuse or breaker sees a sustained fault — coordination is inherent at these speeds.
Panel fit and wire termination
Size S3 frame — 80 mm wide, 140 mm tall, 152 mm deep. Main poles accept stranded wire: 2x 10-70 mm² or 1x 10-70 mm². The coil and auxiliary terminals take solid or stranded 0.5-4 mm² — screw-type only, no push-in. Torque to the Siemens spec on the nameplate; the screw terminals hold up to repeated re-termination better than spring clips in a packed enclosure. The 60 °C ceiling is typical for a ventilated panel — derate the switching frequency if the enclosure ambient pushes above 40 °C.