Oil immersed grounding transformer

　　Oil-immersed grounding transformer is a special type of transformer. Below is a detailed introduction from the perspectives of its structural characteristics, working principle, application scenarios, advantages, and disadvantages:

　　Structural Characteristics

　　Core and Windings: The core is made of high-magnetic-permeability materials stacked together. The windings consist of two mutually insulated windings with different numbers of turns, which are mounted on the core. There is only magnetic coupling but no electrical connection between the two windings. The windings are usually wound with copper or aluminum wires, and the number of turns and wire diameters are designed according to the required voltage levels for transformation.

　　Oil Tank and Oil Conservator: The active part (windings and core) is housed in an oil tank filled with transformer oil. The oil tank is welded from steel plates. For medium and small-sized transformers, the oil tank consists of a tank shell and a tank cover. The active part is placed inside the tank shell, and the tank cover can be opened to lift out the active part for maintenance. The oil conservator serves to buffer and regulate the oil level.

　　Other Components: These include insulating bushings, tap changers, gas relays, thermometers, and oil purifiers. Insulating bushings are used to isolate the high-voltage and low-voltage parts. Tap changers can adjust the output voltage. Gas relays can detect internal fault gases and issue alarms. Thermometers monitor the temperature in real time. Oil purifiers remove impurities and moisture from the oil.

　　Working Principle

　　Electromagnetic Induction: When alternating current passes through the primary winding, an alternating magnetic field is generated in the core. This magnetic field passes through the secondary winding, inducing an electromotive force in the secondary winding and achieving voltage transformation. The secondary winding and the primary winding have different numbers of turns, resulting in different magnitudes of induced electromotive force. When the internal resistance voltage drops are neglected, the voltage magnitudes also differ.

　　Magnetomotive Force Balance: When the secondary side of the transformer is unloaded, only the current flowing through the main magnetic flux (excitation current) flows through the primary side. When the secondary side is loaded and a load current flows, a magnetic flux is also generated in the core, which tends to change the main magnetic flux. However, when the primary voltage remains unchanged, the main magnetic flux remains constant. The primary side must flow two components of current: one is the excitation current, and the other is the current used to balance the load current. This current varies with the load current, and energy transfer between the primary and secondary sides is achieved through this magnetomotive force balance.

　　Application Scenarios

　　Power Systems: In power plants, they convert the high voltage generated into low/medium voltage levels suitable for transmission to households and businesses. In large substations or industrial parks, they can not only handle high-voltage power conversion but also be used for long-distance power transmission, improving the efficiency of the entire power grid. In high-speed railway systems, they ensure the normal operation of trains and provide stable power.

　　Industrial Fields: In the steel industry, they are widely used in equipment such as blast furnaces and rolling mills to ensure normal operation and provide stable and reliable energy. In the petrochemical industry, they are applied in fields such as crude oil processing and oil refining, providing the required stable energy in various links.

　　Advantages

　　Good Heat Conductivity: They can transfer the generated heat out, with better heat dissipation performance than dry-type transformers, making them suitable for long-term operation.

　　Strong Load Adaptability: They have strong cooling capacity and can operate stably in power grid environments with large load variations.

　　Good Economy: They have high operating efficiency, which can reduce energy consumption and lower energy and operating costs.

　　Disadvantages

　　Potential Safety Hazards: They contain flammable and toxic substances. Once leaked, they may cause safety problems such as fires and explosions. Moreover, they are flammable and may burn or explode when exposed to flames, which is also harmful to humans.

　　High Maintenance Costs: They require frequent oil replacement and maintenance work, as well as regular inspections.

　　Environmental Pollution: In long-term use, they generate a large amount of waste oil, causing relatively obvious environmental pollution.

　　Poor Short-Circuit Resistance: Their sealing performance is poor and they are prone to aging, resulting in serious oil leakage at the operation site and affecting the safe operation of the equipment.