Core: The magnetic circuit part of a transformer, usually composed of hot-rolled or cold-rolled silicon steel sheets with high silicon content, thickness of 0.35-0.5mm, and surface coated with insulating paint stacked together. The iron core is divided into two parts: the iron core column and the transverse plate. The iron core column is equipped with windings, and the transverse plate is used to close the magnetic circuit. There are two basic forms of iron core structure: core type and shell type. The core column of the transformer with core type structure is surrounded by the winding, which has a simple structure, easy assembly and insulation, and is therefore widely used; The shell structure transformer core surrounds the winding and has high mechanical strength, but the manufacturing process is complex and requires a lot of materials. It is usually only used for low-voltage high current transformers or small capacity power transformers.

Winding: The circuit part of a transformer, made up of enameled wire wound with a certain number of turns. The winding connected to the power supply is called the primary winding, and the winding connected to the load is called the secondary winding. Transformers can be powered by low or high voltage windings as needed. The low-voltage winding has fewer turns than the high-voltage winding and is composed of thick copper wires; The number of turns in the high-voltage winding is a multiple of the number of turns in the low-voltage winding, and it is composed of thin copper coils.

Oil tank: The outer shell of an oil immersed transformer, which is also the skeleton for placing other components inside the transformer, playing a role in mechanical support, cooling and heat dissipation, and insulation protection. The fuel tank is mainly divided into bucket type fuel tank and bell jar type fuel tank. Bucket type fuel tank is easy to manufacture, saves materials, and has good strength. However, when repairing or inspecting the transformer body, a larger crane must be used to lift the body out of the fuel tank; The bell shaped fuel tank only needs to be lifted open during maintenance, and the body can be exposed without moving, so there is no requirement to install heavy lifting equipment at the operating location.

Insulation sleeve: The output device of a transformer, which connects the high and low voltage leads in the transformer to the outside of the oil tank and plays an important guiding role in the current load inside the device. Transformer bushings are mainly divided into three types: oil oil bushings, oil gas bushings, and oil paper capacitor bushings. Among them, oil paper capacitor bushings are currently the most widely used. The current carrying method is to use cable passing, and the connection of the bushing in the transformer is completed by combining the axial compression force caused by multiple sets of pressure springs.

Tap changer: used to adjust the voltage level of the load center, regulate reactive power, and regulate load current, mainly divided into on load tap changer and off load tap changer. The electrical contact system of a non excited tap changer consists of moving contacts, fixed contacts, and supporting components. Typically, the non excited tap changer, along with its operating mechanism, is installed inside the transformer’s main oil tank.

Other components: There are also some other components inside the transformer, such as insulation materials, transformer oil, respirators, cooling pipes, gas relays, explosion-proof pipes, etc. These components have their own functions and work together to ensure the normal operation of the transformer.