As a key piece of equipment in a power system for voltage transformation and energy transmission, the structural design of a power transformer directly affects its operational reliability, efficiency, and service life. The overall structure consists of an electromagnetic circuit, insulation and cooling system, protection and monitoring devices, and external support components. These components work together to ensure the safe and efficient transfer of energy between high and low voltage levels.
The electromagnetic circuit, composed of the iron core and windings, is the core of the transformer's energy conversion. The iron core is typically made of high-permeability cold-rolled silicon steel sheets stacked along the magnetic flux direction to reduce eddy current and hysteresis losses and form a closed, low-resistivity path, resulting in high magnetic flux coupling between the primary and secondary windings. The windings are divided into high-voltage and low-voltage windings, generally made of high-quality copper or aluminum wire wound on insulating cylinders or support bars. Insulating paper or film is used between layers and turns to ensure electrical insulation and provide mechanical support. The high-voltage and low-voltage windings are arranged concentrically or overlappingly on the iron core columns to accommodate the insulation distance requirements of different capacities and voltage levels. Insulation and cooling systems are crucial for ensuring the safe operation of transformers. Transformer oil, serving both insulating and heat dissipation functions, fills the tank and conducts heat from the windings and core to the tank surface or radiators. Large transformers are often equipped with plate radiators, forced oil circulation cooling devices, and fans to improve heat dissipation efficiency. The tank body is welded from steel plates, possessing sufficient mechanical strength to withstand internal oil pressure and external environmental stress. It also includes an oil conservator (expansion tank) to balance oil level fluctuations due to temperature changes and prevent moisture intrusion.
Protection and monitoring devices include various switches, relays, and sensors. Gas relays can detect gases generated by internal faults and promptly alarm or trip; pressure relief valves quickly release pressure when internal pressure rises abnormally, protecting the tank from damage; oil thermometers and winding thermometers monitor operating temperature in real time, providing a basis for load dispatching. Modern transformers can also integrate online monitoring systems such as partial discharge monitoring and dissolved gas analysis in the oil, enabling early warning of latent faults.
External support components include the base, bushings, and valves. Bushings connect the winding leads to the external circuit while ensuring the insulation and sealing of the high-voltage leads; valves are used for oil injection, sampling, and venting, facilitating inspection and maintenance. The overall structure design must comprehensively consider electromagnetic load, thermal load, mechanical strength, and environmental conditions to ensure stable performance during long-term operation.
Therefore, the power transformer structure is a highly integrated engineering system, reflecting the precision of electromagnetic design and incorporating the comprehensive application of materials, thermal, and monitoring technologies, providing a solid foundation for the safe and economical operation of power systems.