The present disclosure relates to a transformer arrangement 1 comprising a transformer tank 2 for a liquid-filled electrical transformer, an expansion tank 4, and piping 8 connecting the transformer tank with the expansion tank for enabling liquid of the liquid-filled transformer to flow between the transformer tank and the expansion tank via the piping. The piping comprises a valve 7. The valve is configured for allowing the liquid to flow from the transformer tank to the expansion tank when the pressure of the liquid in the transformer tank is above a predefined first threshold and for preventing the liquid to flow from the transformer tank to the expansion tank when the pressure of the liquid in the transformer tank is below the predefined first threshold. The valve is also configured for allowing the liquid to flow from the expansion tank to the transformer tank when the pressure of the liquid in the transformer tank is below a predefined second threshold and for preventing the liquid to flow from the exp
