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Structure and Main Components of Oil-immersed Transformer

Ⅰ. Main structure of oil-immersed transformer

The main structure of oil-immersed transformer is composed of body, oil tank, cooling device, protection device and outlet device. The body includes iron core, winding (coil), insulation, lead wire and tap changer; the fuel tank includes the fuel tank body and fuel tank accessories (oil drain valve, grounding screw, trolley, nameplate, etc.); the cooling device includes radiator and cooler; Protection devices include oil conservator, oil level, safety airway, moisture absorber, temperature measuring element and gas relay; outlet devices include high and low voltage bushings.

Ⅱ. The main components of oil-immersed transformers

1. Iron core: The iron core is the main body of the magnetic circuit of the oil-immersed transformer. The iron core structure is divided into two types of transformers: core structure and shell structure. Core transformer: The primary and secondary windings of the core transformer are set on the two core columns of the core. The structure is simple, and the power transformers all adopt the core structure. Shell-type transformer: The iron core of the shell-type transformer wraps around the top, bottom and sides of the group. The manufacture is complicated, and small dry-type transformers are mostly used.

2. Winding (coil): The winding is the circuit part of the oil-immersed transformer, which is wound with insulated copper wire or aluminum wire. The role of the winding is the carrier of the current, generating magnetic flux and induced electromotive force. Divided into high-voltage windings, low-voltage windings, concentric windings and overlapping windings

3. Accessories: The accessories of power transformers include fuel tanks, oil pillows, tap changers, safety air ducts, insulating bushings, etc. Its function is to ensure the safe and reliable operation of the transformer.

The oil tank is the shell of the oil-immersed transformer, which is used to dissipate heat and protect the body (the body of the transformer is placed in the oil tank), and there is transformer oil for insulation in the tank. Oil conservator (oil pillow): Installed on the fuel tank to isolate the inside of the fuel tank from the outside world. Safety airway (explosion-proof pipe): Installed on the top cover of the fuel tank to protect the equipment and prevent damage to the fuel tank in case of failure. When the transformer breaks down and a large amount of gas is generated, the pressure in the fuel tank increases, and the gas and oil will break through the explosion-proof membrane and spray out to avoid the fuel tank from bursting.

Gas relay: Installed in the pipeline between the oil tank of the transformer and the oil conservator, the main protection device. Tap changer: By connecting the switch with different joints, the number of turns of the original winding can be changed to achieve the purpose of adjusting the voltage. The tap-changer is divided into on-load tap-changer and off-load tap-changer. Insulating sleeve: Installed on the oil tank cover of the oil-immersed transformer, the function is to lead the end of the coil lead out of the oil tank and insulate the lead wire from the oil tank. Porcelain insulating bushings are used for voltages lower than 1KV, air-filled or oil-filled bushings are used for voltages of 10-35KV, and capacitive bushings are used for voltages higher than 110KV.

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