During the field measurement error test of capacitor voltage transformer（CVT）

it is necessary to connect a test lead on the primary measurement of the tested CVT and the standard CVT.The angle between the lead and the CVT shell will couple to produce distributed stray capacitance

which will be superimposed on the CVT’s own partial voltage capacitance

thus affecting the accuracy of error measurement.Based on the analysis of CVT structure and the coupling characteristics of distributed capacitance

an additional error estimation model caused by the change of primary lead with the change of coupling angle is established.The influence of different coupling angle on the CVT ratio test error is analyzed through a case

and compared with the field test results.The results show that the smaller the angle between the primary lead and CVT is

the larger the error of equivalent distributed capacitance is.