Rated for 1.5 kW at 400...440 V AC 50/60 Hz, it steps up to 2.2 kW at 500 V AC and 3 kW at 690 V AC, covering a useful spread of three-phase motor loads in European and North American voltage systems. The 24 V DC control circuit draws 130 mA peak on closing with the LUB12 interface, settling to 60 mA sealed — numbers that matter when sizing the control transformer or DC supply for a multi-starter panel. Utilisation categories AC-41, AC-43, and AC-44 mean it handles resistive, motor, and lightly inductive loads respectively, with the AC-44 rating confirming it can switch motor loads up to its rated power without derating.
Protection functions and trip behaviour
This unit provides earth fault protection, protection against phase failure and phase imbalance, and overload and short-circuit protection, all with a manual reset that requires a physical button push after a trip. The thermal overload curve is Class 10, frequency-compensated 40...60 Hz and temperature-compensated -25...70 °C per IEC 60947-6-2 and UL 508 — meaning it tracks motor heating closely enough to protect a standard squirrel-cage motor without nuisance tripping on a normal start. Tripping threshold is 14.2 x Ir +/- 20 %. Phase failure sensitivity is built in — if one phase drops, the unit trips within the operating time of 35 ms opening (with LUB12, LUB32, or LUB38 control circuit interfaces).
Dimensions are 45 mm wide, 66 mm high, and 60 mm deep, fitting the standard TeSys U footprint that rows up neatly on DIN rail or a backplate. Rated insulation voltage is 690 V per IEC 60947-6-2 and 600 V per UL 60947-4-1 and CSA C22.2 No 60947-4-1, with safe separation of 400 V SELV between control/auxiliary circuits and the main circuit. Standards compliance includes EN/IEC 60947-6-2, IEC 60947-6-2, UL 60947-4-1 with phase barrier, and CSA C22.2 No 60947-4-1 with phase barrier — covering the main global certification schemes for motor starters.
If you're holding a legacy BOM that calls out an older TeSys U control unit, the LUCB05BLTQ is the direct functional equivalent for the 1.5 kW / 400 V class — no adapter or wiring change needed.