Dead tank capacitor voltage transformer（hereinafter referred to as dead tank CVT）is a kind of new type voltage transformer insulated by SF

6

gas for UHV GIS projects

which

compared with the traditional column CVT

has the advantage that the capacitance is free from the influence of stray capacitance. The error of the dead tank CVT is susceptible to such factors as temperature and frequency due to limitation of the characteristics of the capacitive device itself. For better understanding of the long-term operation condition and the error of the 1 000 kV dead tank CVT in operation

the error influencing factor is analyzed in this paper and the live

assessment system

including temperature monitoring system

fault recording system and error calibration system

is set up. The 0.2-level capacitor voltage transformer and the dead tank capacitor voltage transformer are used for error comparison so to achieve the comparison calibration and longterm live test at variation of different temperature. The study shows that the 1 000 kV dead tank CVT has good insulation performance

reasonable temperature error and can meet the needs of projects. The study results in this paper lay a foundation for the engineering application of the 1 000 kV dead tank CVT.