With the wide use of capacitor voltage transformer（ CVT） in power system

some problems occurs in the operation

in which the common one is breakdown fault of internal capacitor element. Although CVT capacitor element has high dielectric margin

yet the withstand voltage fature of the element and influence of definite number of brokendown elements on safety of complete CVT are not tested and studied. In this paper

the element breakdown and integrated withstand voltage test and study for complete set or single voltage divider’s capacitance is performed

whether existance of complete breakdown after breakdown of a certain number of capacitance components is verified and probable threshold applicable for CVT on-line monitoring system is obtained.