Oil-immersed Transformer

　　Comprehensive Analysis of Oil-Immersed Transformers

　　I. Basic Overview

　　An oil-immersed transformer is a type of power transformer in which the transformer core and windings are submerged in insulating oil. The insulating oil not only serves as an electrical insulator but also dissipates heat generated during the operation of the transformer, ensuring that it operates within a suitable temperature range for stable performance. Its naming typically follows certain rules. For example, it may start with "S", where "S" represents three-phase, followed by a combination of numbers and letters indicating the capacity, voltage level, design sequence number, etc. The naming conventions may vary among different manufacturers and product series.

　　II. Technical Characteristics

　　Superior Heat Dissipation Performance

　　Insulating oil has a high specific heat capacity and good thermal conductivity, enabling it to quickly absorb the heat generated inside the transformer and dissipate it into the surrounding environment through radiators. Take a medium-capacity oil-immersed transformer as an example. When operating at full load, the insulating oil can rapidly carry away the heat produced by the core and windings, keeping the transformer temperature within a reasonable range. Compared with some transformers that rely solely on air cooling, it has higher heat dissipation efficiency and can adapt to higher load operations.

　　Excellent Insulation Performance

　　The insulating oil provides a reliable electrical insulation environment, effectively isolating the various live parts of the transformer to prevent short circuits and breakdowns. In high-voltage environments, the insulating oil can withstand high electric field strengths, ensuring the safe operation of the transformer. For instance, in substations of some high-voltage transmission lines, oil-immersed transformers can operate stably, providing reliable voltage transformation for the power system.

　　Relatively Low Cost

　　From a manufacturing perspective, the structure of an oil-immersed transformer is relatively simple, the production process is mature, and the cost of raw materials is relatively low. Compared with some transformers that use special insulating materials and complex cooling systems, it has a significant advantage in manufacturing cost. For projects that are more cost-sensitive, such as small factories and rural power grid upgrades, oil-immersed transformers are an economical choice.

　　High Operational Stability

　　After long-term development and improvement, the technology of oil-immersed transformers has become very mature, and their operational stability has been widely recognized. As long as regular maintenance and overhauls are carried out, their service life is usually long, and they can provide reliable power supply to users. In places with high requirements for power supply reliability, such as large industrial enterprises and hospitals, oil-immersed transformers are also widely used.

　　III. Structural Components

　　Core

　　It is generally assembled from silicon steel sheets. Silicon steel sheets have the characteristics of high magnetic permeability and low loss, which can effectively reduce hysteresis loss and eddy current loss in the core. The shape of the core is usually either core-type or shell-type. The core-type core has a simple structure and is convenient to manufacture, so it is more widely used; the shell-type core has better mechanical strength and short-circuit withstand capability.

　　Windings

　　They are divided into high-voltage windings and low-voltage windings and are usually wound with copper or aluminum wires. The number of turns and wire diameter of the windings are designed according to the rated voltage and capacity of the transformer. To enhance the insulation performance, insulating materials such as insulating paper and insulating cylinders are set between the windings.

　　Insulating Oil

　　It is a key component of the oil-immersed transformer, and mineral insulating oil is generally used. It not only provides insulation and heat dissipation but also has a certain arc-extinguishing performance. During use, it is necessary to regularly detect and maintain the insulating oil to ensure that its performance meets the requirements.

　　Oil Tank

　　It is used to contain the insulating oil and the main body of the transformer and is usually welded from steel plates. The oil tank is equipped with accessories such as radiators, oil level gauges, and thermometers to monitor and control the operating status of the transformer. The radiators can increase the heat dissipation area and improve the heat dissipation efficiency; the oil level gauge can visually display the oil level of the insulating oil in the oil tank; the thermometer is used to monitor the oil temperature of the transformer.

　　Oil Conservator

　　It is installed above the oil tank and connected to the oil tank through a connecting pipe. The function of the oil conservator is to regulate the volume change of the insulating oil in the oil tank. When the transformer temperature rises, the insulating oil expands, and the excess oil will enter the oil conservator; when the temperature drops, the insulating oil contracts, and the oil in the oil conservator will supplement the oil tank, thus maintaining a stable oil level in the oil tank.

　　Explosion-Proof Vent (Safety Airway)

　　Also known as a bursting disc, it is installed on the top of the oil tank. When a serious fault occurs inside the transformer, generating a large amount of gas and causing a sharp increase in the pressure inside the oil tank, the explosion-proof vent will rupture, discharging the gas to prevent the oil tank from exploding and protect the safety of the transformer and surrounding equipment.

　　IV. Application Scenarios

　　Power System Transmission and Distribution

　　In the transmission and distribution links of the power system, oil-immersed transformers play an important role. For example, in substations, step-up transformers are used to increase the low-voltage electrical energy generated by power plants to high voltage for long-distance transmission, reducing energy losses during transmission; in the distribution link, step-down transformers are used to reduce the high-voltage electrical energy to a voltage level suitable for user consumption.

　　Industrial Sector

　　Large industrial enterprises usually require a large amount of power supply and have high requirements for the stability and reliability of the power. Oil-immersed transformers can meet the power needs of industrial enterprises and provide a stable power source for various production equipment. For example, in enterprises such as steel mills and chemical plants, oil-immersed transformers supply power to motors, heating equipment, etc. on the production line.

　　Rural Power Grids

　　In rural areas, the power load is relatively dispersed, but the coverage is wide. Oil-immersed transformers have the advantages of low cost and stable operation, making them suitable for use in rural power grids. They can provide power to rural villages, farmland irrigation, etc., improving the power conditions in rural areas.

　　New Energy Power Generation

　　In the fields of new energy power generation such as wind power and solar power, oil-immersed transformers are also widely used. They can transform the voltage of the electrical energy generated by new energy power generation equipment and connect it to the power grid or supply it to local loads. For example, in wind farms, oil-immersed transformers increase the low voltage output by wind turbines to a voltage level suitable for grid transmission.

　　V. Comparison of Advantages and Disadvantages

　　| | Advantages | Disadvantages |

　　| | | |

　　| Oil-immersed Transformers | 1. Superior heat dissipation performance, capable of adapting to high-load operations

　　2. Excellent insulation performance, safe and reliable

　　3. Relatively low cost, economical

　　4. High operational stability, long service life | 1. There is a risk of oil leakage, which may cause environmental pollution

　　2. Large volume, occupies more floor space, inconvenient for installation and transportation

　　3. Requires regular detection and maintenance of the insulating oil, with high maintenance costs

　　4. High fire prevention requirements, not suitable for use in places with strict fire prevention requirements |

　　VI. Maintenance and Care

　　Regular Inspections

　　Regularly check the appearance of the transformer, looking for signs of oil leakage in the oil tank, whether the oil level is normal, and whether the radiators are clean and unobstructed. At the same time, check whether the operating sound of the transformer is normal and whether there is any abnormal vibration.

　　Insulating Oil Detection

　　Regularly take samples of the insulating oil for testing. The testing items include breakdown voltage, dielectric loss factor, water content, etc. Based on the test results, judge whether the performance of the insulating oil meets the requirements. If the performance of the insulating oil is found to have degraded, it should be promptly treated, such as by filtration, regeneration, or replacement.

　　Electrical Tests

　　Conduct electrical tests on the transformer at specified intervals, such as insulation resistance tests, DC resistance tests, and AC withstand voltage tests. Through electrical tests, insulation defects and other problems inside the transformer can be detected in a timely manner to ensure its safe and reliable operation.

　　Accessory Maintenance

　　Regularly maintain and inspect the various accessories of the transformer, such as thermometers, oil level gauges, and fans, to ensure their normal operation. For example, check whether the display of the thermometer is accurate, whether the operation of the fan is flexible, and whether there is any abnormal noise.