How is a transformer oil-filled tank designed for thermal expansion and safety?

Oil expands with temperature, so tanks include space for expansion using either a conservator system or sealed flexible designs. Conservators provide a reservoir that maintains oil level and reduces pressure swings, often with a breather to control moisture intake. Safety devices can include pressure relief, sudden pressure relays, and Buchholz relays in conservator type units. Radiators increase heat dissipation. Spill containment features such as bunds, drain valves, and sampling points support safe maintenance and environmental control.