Abstract: Aiming at the practical operation situation of Hebei Guohua Cangdong Power Generation Corporation Limited, the similarities and differences of the generator non fullphase protection and the breaker non fullphase protection were compared. When the non fullphase operation state occurred and the generator non fullphase protection was not configured, the behavior of the generator negative sequence inversetime limit protection was analyzed. It was pointed out finally that there is certain need to configure the generator non fullphase protection for the unit without generator non fullphase protection, which can cut off the failure parts for shorter time when the non fullphase situation under rated condition occurs; and the safety of the generator will be protected.

Key words: generator, non full-phase protection, breaker, operation