Application of Turn Ratio Tester in the Capacitive VT Test and Problems-solving

Chen Kun, Li Chao
HIMALAYAL - SHANGHAI - CHINA 

Abstract: Whether the turn ratio of current transformer is correct has a direct impact on electricity measurement and protection accuracy while the capacitive current transformer is extensively applied to measure and protect the substation system and equipment. This paper presents the application of three-phase turn ratio & group tester to test the capacitive voltage transformer and illustrates the problems which occur in the on-site measurement and its solutions.   

Key words: Three-phase transformer ratio, capacitive voltage transformer

1.Overview
The voltage transformer can be classified into two categories according to its structure, working principle and application: EVT and CVT. The full name of EVT is electromagnetic voltage transformer, working principle of which is the same as transformer. Its basic structure is composed of iron core, primary winding and secondary winding. This type of transformer has small capacity and is very constant. When running normally, it is close to no-load condition.