Losses and Temperature Rise of Electric Transformers:
Overview:
During operation, the magnetic flux flowing through the transformer core generates losses within the core itself. The current flowing through the windings also causes losses within the windings. Additionally, the leakage magnetic flux caused by the winding current and the core's over-excitation contribute to leakage outside the core, resulting in additional losses in various structural components, such as coils, core structures, core laminations, and the oil tank. There are also losses associated with the cooling system, including the oil pump and fans.
All types of losses are converted into heat. Part of this heat is used to raise the temperature of various components, while another part is dissipated to the cooling medium surrounding these components.
The insulation materials used in transformers have a certain thermal lifespan. For example, the heat resistance grade of oil-immersed transformers is Class A, where the long-term operating temperature for Class A insulation materials is 105 degrees Celsius.
