Localizing Hotspot in an Oil Immersed Distribution Transformer Using Finite Element Analysis
E G P Ediriweera, Kithmin Wickramasinghe, K R I Sithmini, E A A G Ekanayaka, Rasara Samarasinghe, J. R. Lucas
Abstract
In the electric power system the health of the distribution transformer is essential in maintaining a healthy power system. An overheated transformer leads to reduction in its life. Heat generation caused in the core and in the conductor due to losses, affect the performance. Monitoring the hotspot temperature, where the temperature is the highest within the transformer, leads to many benefits, such as the reduction of transformer aging due to partial discharges and permitting optimum loading to be carried out. In this paper, a Finite Element Method based thermal model has been developed considering the conjugate heat transfer and fluid dynamics mechanisms, to determine the temperature distribution of a distribution transformer. Using the manufacturer provided data for a 160 kVA distribution transformer, the top-oil temperature has been validated and found to be within 1°C. Based on the temperature profiles determined, the location of the hot spot has been accurately predicted to permit insertion of sensitive temperature monitoring fiber-optic sensors during distribution transformer manufacture.