400 V Cement Mixers

Current draw follows the motor rating: a 1.1 kW three-phase mixer takes about 2.5 A per phase in steady running, a 1.5 kW machine around 3.5 A. Inrush reaches several times that, which is why the standard is a 16 A CEE socket with a type C 16 A breaker — a characteristic that rides out the starting peak. A site circuit is additionally protected by a 30 mA residual current device.

The gap shows up on starting under load and over long runs. A three-phase motor comes up with full torque, so it turns a drum full of mortar even after a break of several minutes, and at 1.1 kW it loads each conductor with roughly 2.5 A instead of the 7.5 A a 230 V machine needs. Lower current means smaller losses in the cable: on a 50 m extension the drum keeps its speed. A 400 V machine is also rated for continuous duty across a whole shift, whereas a single-phase unit running 2–4 minute batches needs pauses for the winding to cool down.

Three-phase machines are fed with five-core rubber-sheathed H07RN-F cable terminated in 16 A CEE plugs and sockets. A 5×2.5 mm² cross-section covers runs of about 50 m with motors up to 1.5 kW; beyond that, move to 5×4 mm². Always unwind the cable fully — a coiled reel heats up and loses 30–40 percent of its rating. Keep couplings off the ground: connectors lying in water are the most common reason a residual current device trips.

Generator supply is the normal solution on plots without a mains connection, provided there is headroom for the starting surge. The unit needs a three-phase 400 V output with a 16 A CEE socket, and its rating is picked three to four times above the motor: for a 1.1 kW mixer that usually means around 4–6 kVA. An undersized generator sags in voltage when the drum starts under load and cuts out. Equipment for that kind of station is listed under generators.