Study on the influence of secondary load to the error characteristics of CVT

Abstract

With the advantage of high dielectric strength and low cost, capacitive voltage transformers (CVTs) have been applied to measure the voltage in power grid widely. Recently, CVTs own the problem of big error, insulation performance degradation and high failure rate due to the complicated environment. Secondary load is an important factor to impact CVT's accuracy by analysis. Consequently, we established a simplified analysis model of CVT to research the influence mechanism of secondary load and a test platform of 220kV CVT to research its error characteristic with different load capacity and power factors. The experimental results showed secondary load capacity and power factors should be kept in a reasonable range. Moreover, it should be paid particular attention to the light load, no load and the situation when the power factor was less than 0.8, because the CVT of which faced the risk of exceeding error.