Square D LUCA18FU Thermal Overload Relay

LUCA18FU is a three-pole TeSys Ultra standard control unit that provides integrated thermal overload protection for three-phase motors in the 4.5 to 18 A range. It accepts coil voltages from 110 to 240 VAC or 110 to 240 VDC and is rated for line voltages up to 690 VAC, with class 10 thermal protection for fast, reliable trip performance. The unit delivers overload and short-circuit protection and includes earth-fault protection plus safeguards against phase loss and phase imbalance as part of motor-starter circuitry. Designed for use in TeSys Ultra motor-starter assemblies, LUCA18FU coordinates protection within industrial control panels and supports compact, integrated motor protection solutions.