油浸式电气设备防爆技术演变及其与系统短路容量关系分析OA

In order to analyze the ability of large oil-filled equipment to withstand internal large arc fault,the technical development of oil-immersed equipment such as oil switch,oil-immersed current/voltage transformer,oil-paper bushing and oil-immersed power transformer in explosion-proof and fire-proof is reviewed in this paper.There is a trend of using SF6 or dry-type insulation instead of oil-immersed equipment in less oil equipment.However,similar technical routes cannot be adopted for large power transformers.Therefore,based on the analysis method of ability of large oil-immersed transformer tank withstand internal short-circuit arc fault,the relationship between transformer tank volume and system short-circuit current are analyzed in this paper.It is considered that under the factors of the increase of the short circuit capacity of the system,the basic physical properties of insulating liquid's incompressibility and the limited increase of the volume of tank,the ability of tank withstand internal short-circuit arc fault is exceeded,when the oil-immersed transformer is faced with internal arc short circuit fault.In this paper,it is revealed that the essence of the explosion and fire problem of large oil-immersed transformer is due to the increasing transmission capacity of power grid,and the corresponding increase of the short-circuit capacity/current of the system exceeds the upper limit of the ability of tank withstand internal short-circuit arc fault,which has limited volume.