It sits in the TeSys U family as the brains of the motor starter — handling overload, short-circuit, earth fault, and phase failure protection in one plug-in module that snaps into the power base. Rated for a 0.25 kW three-phase motor at 400...440 V AC 50/60 Hz, this unit covers small pump, fan, and conveyor drives in control panels. The control circuit accepts 110...240 V AC or 110...220 V DC, drawing 280 mA during closing and 25...35 mA sealed depending on the control voltage interface (LUB12, LUB32, or LUB38). Protection is Class 10 thermal overload with temperature compensation from -25 to 70 °C, and the magnetic trip threshold is set at 14.2 x Ir ±20 % for short-circuit clearance. The manual reset keeps the operator in control after a fault — no automatic restart on a stalled motor.
The LUCB1XFUTQ carries EN/IEC 60947-6-2 and UL 60947-4-1 / CSA C22.2 No 60947-4-1 approvals (with phase barrier), covering motor starter and controller applications across North American and European jurisdictions.
The control unit plugs into the TeSys U power base from the front face — no tools needed for replacement. Dimensions are 45 mm wide, 66 mm high, and 60 mm deep, fitting standard 45 mm per-function slot spacing on DIN rail. IP20 on the front panel and wired terminals; IP40 on the front panel outside the connection zone. Operating altitude is rated to 2000 m without derating. The unit withstands 10 gn shock with power poles open and 15 gn closed, plus vibration of 2 gn (poles open) and 4 gn (poles closed) across 5...300 Hz.
Electrical environment
Utilisation categories AC-41, AC-43, and AC-44 cover resistive, mixed, and highly inductive motor loads. The unit provides safe separation (SELV) at 400 V between control/auxiliary circuits and the main circuit per IEC 60947-1. Immunity to microbreaks is 3 ms; voltage dips down to 70 % for 500 ms are tolerated per IEC 61000-4-11. Heat dissipation is 2 W with LUB12 control interface, 3 W with LUB32 or LUB38. Fire resistance meets 960 °C on live-part supports and 650 °C general per IEC 60695-2-12.