In view of the failure of the voltage tolerance curve in the current two-dimensional plane of amplitude and duration to fully describe the sensitivity of equipment

a three-dimensional model for the sensitivity of low-voltage releases to voltage sags considering the point-on-wave of voltage sag initiation is proposed based on a large number of experimental data. First

the working principle of low-voltage releases is explained on the basis of Chinese National Standards GB 14048.1—2006. Secondly

in conjunction with relevant foreign and domestic research results and Chinese National Standards GB/T 17626.11—2008

the influence of point-on-wave of voltage sag initiation on the equipment sensitivity is discussed. Thirdly

six mainstream types of low-voltage releases are compared in the voltage sag sensitivity test

the results showing that the sensitivity of low-voltage release to voltage sag is closely related to its type and the point-on-wave of voltage sag initiation. Finally

test results of various low-voltage releases are integrated and their extreme processing is conducted. By adopting the surface fitting principle

a three-dimensional sensitivity model suitable for all types of low-voltage releases is developed from voltage sag amplitude

duration and point-on-wave of voltage sag initiation. This work is supported by Key Program of National Natural Science Foundation of China (No. 50937001) and Fundamental Research Funds for the Central Universities (No. 2012ZM0018).