Combination of non-contact and contact measuring methods for the analysis of the structural condition of dry transformers

Abstract

The article describes the non-contact and contact analysis of 800 kVA dry power transformers with epoxy-resin insulation using an acoustic camera and a frequency analyzer with automatic sweeping for low-middle frequency areas. Power transformers are most often used for analysis of construction components (core, windings, taps). The electric non-rotate machine creates electromagnetic and acoustic emissions, which may be used to analyze the dry transformers during its operation. Non-contact online diagnostic methods have many advantages over offline methods in that it is not necessary to shut down the transformer from the operation, and in addition, the condition and behavior of the machine during its normal operation are analyzed. The article presents the analysis and comparison of structural parts of the distribution dry transformers at the same type and power. The problem of insufficient or incorrect clamp-screw connection was identified by method SFRA.