An oil-immersed transformer is a transformer that uses mineral oil or synthetic insulating oil as the insulating medium and coolant. In an oil-immersed transformer, both the windings and the core are immersed in transformer oil to protect the internal components from the external environment.
How does an oil-immersed transformer work?
The working principle of an oil-immersed transformer is based on the law of electromagnetic induction. When the primary winding (also called main coil) is connected to an AC power source, an alternating magnetic flux is generated in the iron core. This alternating magnetic flux passes through the secondary winding (also called auxiliary coil), thereby generating an induced electromotive force in the secondary winding. By adjusting the turns ratio of the primary winding and the secondary winding, the voltage can be increased or decreased, which is the transformers voltage transformation function.
Specifically, when AC current passes through the primary winding, an alternating magnetic field is generated in the iron core. This magnetic field passes through the secondary winding, and an induced electromotive force is generated in the secondary winding due to electromagnetic induction. The magnitude of the induced electromotive force is related to the turns ratio of the primary winding and the secondary winding, the magnitude of the magnetic flux, and the frequency of the AC. According to Faradays law of electromagnetic induction, the induced electromotive force E can be expressed as:
E = 4.44fNΦm
E is the effective value of the induced electromotive force, f is the frequency of the AC, N is the number of turns of the winding, and Φm is the maximum value of the main magnetic flux.
Since the number of turns of the secondary winding is different from that of the primary winding, the magnitude of the induced electromotive force is also different, thereby realizing voltage conversion. When the number of turns of the secondary winding is greater than that of the primary winding, the output voltage will be higher than the input voltage, realizing the boost function; otherwise, the step-down function.
Working process of oil-immersed transformer
1.Connecting power: When the primary winding is connected to the AC power supply, an alternating magnetic flux will be generated in the iron core.
2.Generate induced electromotive force: The alternating magnetic flux will pass through the secondary winding and generate an induced electromotive force in it.
3.Achieving voltage conversion: The voltage is increased or decreased by adjusting the turns ratio of the primary winding and the secondary winding.
4.Heat transfer and cooling: The heat generated inside the transformer is transferred to the radiator through the insulating oil and dissipated into the air.
5.Oil level adjustment and protection: The oil pillow automatically adjusts the oil level to ensure the normal operation of the transformer oil; the respirator absorbs and purifies the moisture and impurities in the transformer oil; the explosion-proof pipe quickly releases the pressure when a fault occurs inside the transformer.
As an indispensable and important equipment in the power system, the working principle of the oil-immersed transformer is based on the law of electromagnetic induction. Through the coordinated work of the core, winding, oil tank, insulating oil, radiator and other components, the oil-immersed transformer can realize the transmission and distribution of electric energy and ensure stable operation at high temperatures. Understanding the working principle of the oil-immersed transformer and the role of its various components is of great significance for the safe and stable operation of the power system.
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