The Siemens SIRIUS 3RT1076-6QF35 is a size S12 power contactor rated for 400 A at 24 V in AC-1 duty (resistive load). For motor loads (AC-3), the switching frequency is 420 operations per hour, which is typical for a contactor this size: it handles frequent starting but not high-inertia reversing every few seconds. The coil is rated 96-127 V AC/DC, meaning it pulls in reliably across that range and drops out below the lower threshold. Opening delay is 80-100 ms on both AC and DC supplies, so it's not a fast-acting device — expect that lag if you're coordinating with a safety relay or a fast solid-state switch.
Mounting is screw fixing — no DIN-rail snap-on here. The contactor measures 214 mm high, 180 mm wide, 225 mm deep, so it needs a dedicated backplate or sub-panel, not a standard DIN-rail enclosure. That's tighter than many smaller contactors; plan the gland plate and busbar routing accordingly. The main power terminals accept stranded cable from 70 mm² up to 240 mm² — that's substantial cable, so expect large lugs and a torque wrench. Auxiliary terminals accept 2x 0.5-1.5 mm² or 2x 0.75-2.5 mm² solid, or up to 4 mm² max. Coil terminals are screw-type, same as the auxiliaries. Ingress protection is IP00 on the body, IP20 on the front with the cover or box terminal fitted. That means the contactor itself is not touch-safe without the cover — it's intended for a closed panel, not a standalone installation.