Structure and Components of Oil-immersed transformer

An oil-immersed transformer consists of several key components:

Core and Windings: The core is typically made of stacked silicon steel sheets that provide a path for the magnetic field. The windings are insulated coils that carry the electrical current. In oil-immersed transformers, the core and windings are submerged in oil to ensure effective cooling and insulation.
Transformer Oil: The oil used in these transformers is specifically designed to have high dielectric strength and thermal conductivity. It serves to cool the transformer by absorbing the heat generated by the windings and core through convection and radiation.
Tank: The transformer is housed within a tank that is filled with oil. The tank is designed to be robust and sealed to contain the oil and provide physical protection to the internal components.
Bushings: High voltage and low voltage bushings transmit the electrical energy from the transformer to its next destination. They are made of insulating materials to prevent electrical leakage.
Breather: A breather system allows the oil to expand and contract with temperature changes without coming into contact with the atmosphere, which would risk contamination.
Oil Conservator (Pillow): This is a separate tank that helps maintain the oil level and quality by providing a reservoir for oil expansion and contraction.
Pressure Relief Device: This is a safety feature designed to release pressure in the event of an internal fault that could cause a rapid increase in pressure.
Cooling System: Oil-immersed transformers may have radiators or cooling fins to dissipate heat more effectively.
Tap Changer: This allows for the adjustment of the transformer's output voltage under different load conditions.

Working Principle

The working principle of an oil-immersed transformer is based on electromagnetic induction. When an alternating current (AC) is applied to the primary winding, it creates a varying magnetic field that induces a voltage in the secondary winding. The ratio of the primary to secondary windings determines the transformation ratio, which is how much the voltage is stepped up or down.

Advantages

Efficient Cooling: The oil provides superior cooling compared to air, which allows the transformer to handle higher loads and operate at higher temperatures without overheating.
Insulation: The oil also serves as an excellent insulating medium, reducing the risk of electrical faults and improving the safety of the transformer.
Noise Reduction: The oil-filled environment helps to dampen the noise produced by the transformer, making it more suitable for noise-sensitive areas.
Longevity: The oil helps to prolong the life of the transformer by reducing the rate of deterioration of the insulation and other internal components.
Environmental Compatibility: Some oil-immersed transformers use environmentally friendly vegetable oil instead of mineral oil, reducing the environmental impact.
Safety: The oil acts as a fire-resistant barrier, reducing the risk of fire in the event of an internal fault.