In order to quickly remove the mid-low voltage bus fault arranged in the cabinet, according to the characteristics of the switch cabinet sealing structure fault, combined with the operation mode, a new type of medium and low voltage fast bus precise protection is given. Based on the requirements of arcing test and the recording data of actual operation faults, it is found that the equipment faults arranged in cabinet will eventually develop into three-phase short-circuit faults. New protection only starts when the three-phase fault appears, at the same time judges system operation mode combined with three-phase fault current, achieves protection and the way intelligent integration and strategy which is chosen to jump bus coupler after comprehensive judgement, shortening the time of isolation fault. In the meanwhile using the three-phase voltage lockout, it puts an end to risks of false action of ring network and remote area. The new protection breaks through the disadvantages of the traditional multiple protection, and can efficiently and quickly remove the bus fault, thus solving the extremely urgency problem of today's power grid. Simple installation, less wiring, and suitable for the needs of field and industrialization, is one of the development directions of relay protection. This work is supported by National Key Research and Development Program of China (No. 2017YFB0903201) and Science and Technology Project of China Southern Power Grid Co., Ltd. (No. GDKJXM20161906).