Experimental study on the low-temperature performance of transformer oil with different trace water content

Abstract

In oil-immersed transformers, the insulation performance of transformer oil is a key factor for the normal operation of transformers. In order to explore the performance of transformer oil under different micro-water content conditions in a low-temperature environment, this paper builds a low-temperature experimental platform with a minimum temperature of -50 °C and selects the commonly used 45# oil as the test oil. Four properties including conductivity and dielectric properties were tested. The research results show that the viscosity of transformer oil increases exponentially with the decrease of temperature, the thermal conductivity first decreases and then increases with the decrease of temperature, the relative dielectric constant increases approximately linearly with the decrease of temperature, and the micro-water content increases. It has little effect on the above three properties; the electrical conductivity and dielectric loss of transformer oil with different micro-water content both increase first and then decrease with the decrease of temperature, and with the increase of micro-water content, the corresponding peak temperature also increased.