Simulation of oil flow process of insulation structure for high efficiency cooling shell transformers

Thermal stress is one of the major causes of deterioration of insulation material for power transformers. An efficient cooling system is important to keep the operating temperature at lower levels. In shell-form transformers, the insulation structure plays an important role in not only insulation but also cooling efficiency. It is known that insulation of shell-form transformers is barrier insulation, composed of spacers. Though some experimental suggestions are given to improve the cooling oil flow for shell-form transformers, effect of various spacer shapes and distributions which are important for cooling oil flow are not discussed before. Simulations of oil flow process under various insulation structures are implemented in this paper. Accurate models are made for the insulation structure of a 630KVA shell-form transformer in order to optimize the cooling efficiency of insulation structure in this paper. Suitable insulation structure is suggested which is very helpful for optimizing design and improving manufacture technologies for shell-form power transformers.