The Methodology of High-Voltage Instrument Transformers Technical State Index Assessment

The paper presents a methodology for technical state assessment of high-voltage instrument current and voltage transformers based on the basic requirements, imposed by governmental regulations. At present, in Russia the methodology of technical state assessment is implemented only for the main technological equipment, among which only the power transformers are considered among 110 kV outdoor equipment. The initial dataset for the presented study was composed of technical diagnostic results and testing data of 110 kV instrument transformers, installed at the outdoor switchgear of thermal power plant. The developed methodology includes the analysis of the power equipment structure, allocation of sub-systems, evaluation criteria and a list of essential parameters, technical state assessment methodology, list of the boundary values, formulation of standard recommendations corresponding to different values of technical state index. The presented approach is validated by providing technical state index calculation results along with failure statistics analysis of the regional power system.