Oil and winding temperature control in power transformers

The temperature of oil and paper is crucial in power transformers. In the case of high temperature, the insulation can carbonise and produce gasses, reducing the lifetime of the transformer drastically. One method of effective cooling of windings is to introduce barriers so that the oil flows between discs and not around them as it would do otherwise. This method is well known but an analytical approach would be in place in order to estimate the accurate result of placement of such barriers. In this paper, the Finite Element program COMSOL is used to make such calculations and decide the optimal placement of barriers in a winding. It has been shown that even few barriers reduce the oil and paper temperature significantly. A method to make such calculations is introduced.