Effect of temperature on tensile and creep characteristics of aluminum wire used in 25 kVA distribution transformers

The reliability of power distribution system to a great extent depends upon the reliability of distribution transformers, which in turn is determined by materials and methods used in their construction apart from the service conditions. This paper presents the tensile and creep characteristics of aluminum wire (electric conductor grade aluminum alloy 1350) used in the windings of the 25 kVA distribution transformers. The effect of the temperature along with the stress on the engineering creep curve has been presented. The dependence of the tensile strength on the temperature (room temperature to 140 °C) has been presented. And, a typical stress-strain curve at 140 °C has also been presented. The SEM fractographs of the creep and tensile fractured surfaces have been presented to show the mode of the fracture. The image analysis results of SEM micrographs have also been presented. The inclusions present in the aluminum matrix of the winding conductors can influence the creep and tensile properties which in turn affect the life and reliability of the distribution transformers.