Accuracy test is important part of sampling test for CVT. At present

the online monitoring method cannot accurately assess the abnormal state. Therefore

the accuracy assessment method of CVT

which is suitable for gradual error

is proposed. In this paper

the test platform of measurement error and comparison for CVT is set up. The gradual error under temperature

frequency and other disturbances are evaluated in combination with traditional PCA analysis and improved PCA analysis. The test shows that the improved PCA method can automatically adjust Q threshold with higher evaluation accuracy and is better than the traditional PCA method. With the increase of temperature

ratio difference of CVT can decreases and angle difference of CVT can increase.While

with the increase of frequency

both ratio and angle difference of CVT decrease. The method in this paper provides a definite technical support for accuracy assessment of CVT under gradual error.