Abstract: In response to the complex operation mode and fault development process of the power grid caused by the large-scale integration of new energy, along with a case involving multiple transformer gap protection actions caused by a complex fault on a 110 kV line.This article introduces the principles, composition, and setting principles of transformer gap protection.It analyzes the operational behavior of various protection devices within the 110 kV system during the development of the accident.The article focuses on changes in the busbar and zero-sequence voltage of the 110 kV system resulting from alternations in the neutral grounding operation mode.Additionally, it summarizes the factors to be considered when setting the operating time of the 110 kV gap protection, providing practical engineering insights for power grid accident analysis and transformer gap protection configuration principles.