The Effect On CVT Dielectric Loss Test Results Of Various Test Method

As the developing of our nation's power grid and the advancing of voltage grade, capacitance voltage transformer (shorted form CVT) can be used in the field of high voltage electric power metering, relay protection, instrument direction, high frequency protection and telecontrol channel in electric power carrier communication connection. Compared to the electromagnetic voltage transformer, CVT has the unparalleled advantages. CVT has being used in medium and high voltage system. The work reliability of CVT is very important to safe operation of the entire power grid. In order to ensure safe operation of CVT, CVT should do the preventive test to detect the insulation state, thereinto the measure of dielectric loss angle tangent (shorted form dielectric loss) is one of the most important test of detecting CVT's insulation state.According to actual situation of preventive test of the Zibo power supply company and phenomenon which the results of dielectric loss vary greatly by using the different test connection mode, AI-6000 dielectric loss tester is used to measure the dielectric loss of CVT. From the test, the laws can be obtained that the dielectric loss changes with the test voltage in low-voltage (10kV) and different test method affects the dielectric loss of CVT, and the test confirms the existence of the phenomenon further. The paper combines the test analysis and theory analysis, this phenomenon is expounded. According to the test data and theory analysis, some suggests are given: the dielectric loss voltage should be enhanced in the CVT preventive test; the corresponding test connection mode is advised; the insulation state criterion is put forward; at last, some advices are given to the CVT producer about the manufacturing technology of CVT.