Aimed at overcoming the shortcoming of the current stochastic assessment of equipment sensitivity, an effective new method was proposed which use the voltage sag severity index of each type equipment as stochastic variable and search its objective probability density function based on maximum entropy principle. Then the equipment sensitivity was described by equipment failure rate through cumulative summing method. The detailed stochastic assessment principle and solution method was proposed also. The simulation results of PCs showed that compared with four current probability assessment methods,the proposed method is fit for small samples condition and has well assessment precision and good adaptability.
