Distribution Transformers

Core
The core is composed of silicon steel sheets stacked together with good magnetic conductivity. It forms a magnetic flux closed circuit, and the primary and secondary windings of the transformer are wound on the core.
The transformer core is divided into two structures: core type and shell type. Currently, the widely used transformers are of core type. The core of the core type transformer consists of the core column and the yoke. The core of the oil-immersed transformer has oil channels inside for cooling the core, which facilitates the circulation of transformer oil and also enhances the heat dissipation effect of the equipment.

Winding
The winding, also known as the coil, is the conductive circuit of the transformer. It is made by winding copper wire or aluminum wire into multiple layers of cylindrical shapes. The primary and secondary windings are concentrically arranged on the core column and are insulated from each other. The low-voltage winding is usually inside and the high-voltage winding is outside. The insulating material is wrapped around the wire to ensure insulation between the wires and between the wires and the ground.

Oil Tank
The oil tank is the outer shell of the oil-immersed transformer. Besides holding oil, it is also used to install other components.

Voltage Regulator
The voltage regulator is set up to ensure the stability of the secondary voltage of the transformer. When the power supply voltage fluctuates, the voltage regulator is used to adjust the tap switch of the transformer to ensure the stability of the secondary output voltage. The voltage regulator is divided into on-load voltage regulator and off-load voltage regulator.

Radiator
The radiator is installed on the oil tank wall. The upper and lower parts are connected to the oil tank through pipes. When there is a temperature difference between the upper and lower oil temperatures of the transformer, the radiator forms oil convection, and the cooled oil flows back to the oil tank to reduce the temperature of the transformer oil. To improve the cooling effect, measures such as self-cooling, forced air cooling, and forced water cooling can be adopted.

Oil Sump
The oil sump is also called the oil tank. Transformer oil will undergo thermal expansion and contraction due to temperature changes, and the oil level will rise or fall accordingly. The function of the oil sump is to provide a buffer for the thermal expansion and contraction of the oil, keeping the oil tank always filled with oil; at the same time, due to the presence of the oil sump, the contact area between the oil and air is reduced, which can slow down the oxidation of the oil.

Gas Relay
The gas relay, also known as the gas protection relay, is the main protection device for internal faults of the transformer. It is installed in the middle of the connecting pipe between the oil tank and the oil sump. When a serious fault occurs inside the transformer, the gas relay connects the circuit breaker trip path; when a less serious fault occurs inside the transformer, the gas relay connects the fault signal circuit.

Insulation Bushing
The high and low insulation bushings are located on the top cover of the transformer oil tank. For oil-immersed transformers, porcelain insulation bushings are generally used. The insulation bushing's function is to maintain good insulation between the high and low voltage windings leads and the oil tank, and to fix the leads.

Explosion-proof Tube
The explosion-proof tube, also known as the safety air passage, is installed on the transformer's oil tank. Its outlet is sealed with a glass explosion-proof membrane. When a serious fault occurs inside the transformer and the gas relay fails, the gas inside the oil tank will break through the glass explosion-proof membrane from the safety air passage and prevent the transformer from exploding.