Computational Dielectric Stress Analysis for OLTCs throughout the Product Lifecycle

On-load tap-changers (OLTCs) are devices that permit the change of the turn ratios of transformers without interrupting the load current. They are indispensable for the regulation of electric power and voltage in today's energy networks. A decisive aspect for the selection and design of OLTCs is their insulation co-ordination. Nowadays detailed 3D numerical modelling can strongly support the evaluation and improvement of the insulation co-ordination. The numerical modelling consists of two components: First, an electric field calculation, which can be done using standard commercial software packages. Secondly, an assessment method, that allows for the interpretation of the calculated field distribution, enabling the possibility to decide if a certain field distribution is critical or not…