The Schneider Electric TeSys U LUCA05BLTQ is a standard control unit for the TeSys U motor starter system. It handles basic motor protection — overload and short-circuit — for a 3-phase motor, self-cooled. At 400...440 V AC 50/60 Hz it's rated for 1.5 kW motor power; at 500 V AC that climbs to 2.2 kW, and at 690 V AC to 3 kW. The tripping threshold is fixed at 14.2 x Ir, with a ±20% tolerance, and it's Class 10 thermal overload. The control voltage limits are 20...27 V DC for operation, with dropout at 14.5 V DC — so a saggy 24 V supply won't cause nuisance dropouts unless it dips below that floor.
Where it lives in the panel
The control unit itself is IP20 on the front panel and wired terminals, IP40 on other faces outside the connection zone. The unit plugs into the front face of the power base, so it's a snap-in swap without disturbing the load wiring. Physical footprint is 45 mm wide, 66 mm tall, 60 mm deep — it tucks into a standard DIN-rail layout without hogging space. Operating altitude tops out at 2000 m, so if you're building a panel for a high-altitude installation, you'll need to derate or choose a different variant.
The utilisation categories are AC-41 (resistive), AC-43 (motor starting, plugging, inching), and AC-44 (motor switching with frequent starts). It's phase-failure sensitive — it will trip if one phase drops out, which is a common failure mode that cooks motors. Earth fault protection is also built in. The immunity to microbreaks is 3 ms, meaning a brief power glitch shorter than that won't cause a nuisance trip.