Transformer arrangement and method for controlling pressure in a liquid-filled transformer

A transformer arrangement comprising:

• a transformer tank for a liquid-filled electrical transformer;
• an expansion tank;
• and
• piping, 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 including a valve, wherein the piping includes a first pipe and a second pipe, the first pipe extending between the valve and the transformer tank, the second pipe extending between the valve and the expansion tank, and at the valve, the first pipe is arranged at a non-zero angle relative to the second pipe;
• wherein 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;
• wherein the valve is 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 expansion tank to the transformer tank when the pressure of the liquid in the transformer tank is above the predefined second threshold;
• wherein the expansion tank is positioned relative to the transformer tank such as to allow a top surface of the liquid in the expansion tank to be lower than a top surface of the liquid in the transformer tank;
• and
• wherein a portion of the piping connecting the valve to the expansion tank extends from above the top surface of the liquid in the expansion tank to below the top surface of the liquid in the expansion tank.