What is the difference between LRD** and LR3D** overload relays?
Tesys D line Overload Relays
The LRD** overload has single-phase sensitivity and is not designed for single-phase applications. If current is passed through all three legs of the overload, it is possible to prevent nuisance tripping due to ``phase failure``. The LR3D does not have single-phase sensitivity . It does not require current to be passed through all three legs of the overload and thus would not result in nuisance tripping due to ``phase loss``.