Abstract：The influence degree of voltage sag on equipment is related to the fault removal time of protection

action，the magnitude of sag caused by fault and the tolerance ability of equipment sag. The challenge of

considering voltage sag factors in the protection setting process is to determine a time setting method based on sag

conditions and ensure the rationality of the setting results. A relay protection configuration scheme for distribution

network considering the tolerance of sensitive equipment to voltage sags was proposed. Firstly，the concept of

voltage sag tolerance level of sensitive equipment was introduced，and the severity of voltage sag was judged by

combining the CBEMA characteristic curve of sensitive equipment，and the tolerance ability was graded. Secondly，

on the basis of the original protection action time，the protection action time was set by combining the characteristic curve，and the voltage sag effect was aggregated into the relay protection time setting value. Finally，through the simulation analysis of the actual distribution system in a certain area，it is verified that the relay protection technology can improve the influence of the voltage sag caused by the fault removed by the current protection on the sensitive equipment，and realize the low cost reduction of the voltage sag under the condition of maintaining the protection selectivity.

      Key words：voltage sag；equipment tolerance；CBEMA characteristic curve；optimization