The breathing system of an oil-immersed transformer is of vital importance for maintaining equilibrium between internal and external pressures

with any malfunction potentially disrupting the transformer's stable operation. This study develops a thermal–fluid–structure interaction (TFSI) model to simulate the breathing phenomenon in a 110 kV oil-immersed transformer

addressing the limitations of current manual inspection methods. This model analyses key breathing parameters such as breathing volume and maximum breathing rate

along with their dynamic characteristics under various load factors and ambient temperatures

revealing nonlinear and linear relationships

respectively. To validate the model

the breathing parameters of a 110 kV oil-immersed transformer were monitored over a 7-day period using a breather equipped with a breathing monitoring functionality. Comparison between simulation results and monitoring data for the period from 7 p.m. March 7 to 7 p.m. March 8 revealed discrepancies of 6.93% for the maximum daily breathing rate and 6.73% for maximum daily breathing volume. This study contributes to the field by providing a more accurate and efficient method for analysing transformer breathing dynamics

potentially enhancing early detection of breathing system malfunctions

optimising breather maintenance schedules and improving diagnosis of pressure-related faults in oil-immersed transformers.