Physical simulation of heat exchange between 6(10) kV voltage instrument transformer and its environment with natural convection and insolation

Abstract

This study examines the results of thermal tests on a 6(10) kV digital combined current and voltage transformer conducted in an environmental chamber. This measuring instrument consists of current and voltage transformers, featuring a resistive divider, and is used for commercial and technical electric power accounting. Ambient temperatures and levels of insolation on the transformer surface were set for the environmental chamber, with simulation of voltage transformer functioning in normal and emergency modes. We determined the time needed for the thermodynamic system to move to steady heat exchange mode, and also the final temperatures in the lower resistors and on the surface of the voltage transformer insulation cover. The results of our study have been used in developing algorithms for self-diagnostics of the thermal state of a digital combined transformer.