In the capacitor voltage transformer（CVT）

the capacitor is used as the sensor. The capacitor has temperature drift characteristic

which leads to capacitance variation

and then change voltage division ratio and ultimately affect the accuracy. Accuracy test is performed with the power frequency test transformer before delivery of the product. However

the power is only supplied by the cascade resonant transformer at site installation and the accuracy can also be affected by the different frequencies. In addition

the voltage division variation is led by the injected impedance of the primary equipment. The accuracy can also be affected by the size of high voltage wire and the included angle between the high voltage wire and porcelain. For above reason

unqualified accuracy of CVT often occurs in the acceptance check. In this paper

each influence feature is analyzed and precautions at site are summarized through calculation and actual experience.