The size and position difference of the windings determine the leakage flux path and give rise to unbalance of the short-circuit impedances, which strongly affects the transient behaviour of the transformer. This work proposes a new approach of modelling with magnetic equivalent circuit, making use of the transformer geometry and permeance magnetic equivalent circuit, which is suitable for system-level simulation in terms of complexity. Equivalent model requires limited number of parameters and for verification purposes, FEM simulations as well as measurement on the experimental prototype have been performed.