The LRD10TQ is a differential thermal overload relay from the TeSys Deca range, designed for motor protection in three-phase circuits. Its thermal protection adjustment range of 4 to 6 A sets the full-load current window for the motor it guards — set the dial to the motor's nameplate FLA, and the Class 10A trip curve (per IEC 60947-4-1) will open the contactor within 10 seconds at 7.2× Ir, protecting against locked-rotor or sustained overload without nuisance tripping on normal starts. The relay is rated for power circuits up to 690 V AC (IEC) and 600 V (UL/CSA), with an impulse withstand voltage of 6 kV. Phase failure sensitivity is built in: if one phase drops to 30 % of Ir while the others remain at Ir, the relay trips — critical for preventing single-phasing damage on delta-connected motors. Mounting options include plate or rail (with specific accessories) or directly under the contactor — typical for TeSys D or F contactors in motor starter stacks. The signalling circuit (1 NO + 1 NC auxiliary contacts) is rated at 3 A at 120 V AC-15 and 0.22 A at 125 V DC-13, sufficient for PLC inputs or alarm annunciation.
Integration notes
The LRD10TQ mounts under a TeSys contactor (e.g., LC1D or LC1F series) or on a DIN rail with the appropriate adapter. Screw-clamp terminals accept control and power wiring at 1.7 N·m tightening torque.