FIELDEXPERIENCEUSINGA MICROPROCESSORRELAYTOPROTECT A 14,000 HPMOTOR

Theprotective relays discussed inthis paper along with individual solid-state relaying protect a14,000 HP4-pole compressor induction motor.Allprotection islocated inan outdoor breaker cubicle located ataGulf coast petrochemical plant without thebenefit ofHVAC.Theprotection schemewas designed sothatallfault typesandabnormal operating conditions areproperly detected andcleared. Theinstallation includes unique protection functions forlocked rotor protection, blownfusedetection, customized logic fortheupstream breaker tripping, customized relaydisplay, andcondition monitoring oftheprimary equipment (breaker, current transformer (CT), voltage transformer (VT)etc).A novel approach using non-saturating current andvoltage sensors is also discussed inthis paper.