The transformer is a very important element in the power transmission system. In fact, it is necessary to increase or decrease several times the voltage when transmitting the energy from the power station to the consumption. Consequently, the transformer’s research plays a crucial role in conception and operation. Magnetic circuit plays an indispensable role in the operation of the transformer, but in some cases the its magnetization characteristic is not always provided fully and accurately. The paper proposes a method to build the magnetization characteristic of the transformer magnetic circuit based on a combination of no-load experiment and analytic calculation. The research principle is applied in detail with a ABB distribution transformer. The finite element electromagnetic field problem in a 3D transformer structure was analyzed and calculated to validate the proposal method.

Keywords: Power transformers, magnetization characteristic of magnetic circuit, finite element method, no-load mode, T-shaped equivalent circuit.