Protection of induction motors against single phasing or reverse phasing or unbalance supply is one of the major problems in electrical systems. For safe running of 3-phase motors, special protections that keep a continuous watch on supply conditions are very essentials. The major cause of maxium motors burn-out is overloading which occurs due to unbalance supply or single phasing. Phase failure occurs in case of fuse blown-off, loose connections or loss of phase from supply itself.