Measuring Method Study And Application Of CVT Dielectric Loss And Capacitance

Capacitive Voltage Transformer (CVT), which is widely used in72.5kV～1000kV power system, has developed for over50years abroad. Locally produced CVT also has a manufacturing and operation history of40years and is in the stage of mature. With the wide use of CVT and development of power capacitor insulation technology and material technology, CVT has improved in design and manufacture. CVTs with various new type materials and structure was put into market. Manufactures has done many modifications in material and structure to strain ferro resonance and get better instant response. On the other hand, measuring of CVT dielectric loss capacitance has been ignored. Non-standardization of measuring method has a negative effect to equipment insulation supervision and do no good to the long expected status-based maintenance and smart grid construction.This paper first investigated the present status and development trend, studied the difference in principle and structure of different CVTs in combination with CVT type and failures in Inner-Mongulia VHV power supply bureau. It summarized the related theories, measuring principles and new technology applied and discovered site test method which is compared to other method. The method solved problems like CVT measuring variations, conducting lines dismantling, comparision of C13string C2and self-exciting, test voltage and terminal selection. The standardized method adapts well with CVT material and structure development. Site tests has raised the tips for CVT dielectric loss capacitance measuring. It pointed out that basic tests will pay foundation for status-based maintenance and smart grid construction and should be studied in the same time.