35kV oil immersed transformer

　　Overview of 35kV Oil-Immersed Transformers

　　A 35kV oil-immersed transformer is a crucial electrical device used in 35kV voltage-level power systems. It transforms voltage through the principle of electromagnetic induction, converting 35kV high-voltage electrical energy into lower voltages (such as 10kV, 0.4kV, etc.) suitable for user equipment to meet the needs of different electrical loads. Internally, it uses transformer oil as both an insulating and cooling medium. Transformer oil not only provides excellent electrical insulation performance but also effectively dissipates the heat generated during the transformer's operation, ensuring its normal functioning.

　　Structural Components

　　Iron Core: As the magnetic circuit part of the transformer, it is usually assembled from high-permeability silicon steel sheets to reduce iron core losses. The silicon steel sheets are insulated from each other, which effectively lowers eddy current losses and improves the transformer's efficiency.

　　Windings: These are the electrical circuit parts of the transformer, generally wound from copper or aluminum conductors. They are divided into high-voltage and low-voltage windings, and voltage transformation is achieved through reasonable winding methods and turns ratios. The windings are typically mounted on the iron core limbs and insulated with insulating materials to ensure electrical safety.

　　Oil Tank: Used to hold the transformer oil, it also serves to support and protect the internal components of the transformer. The oil tank is usually welded from steel plates and has good sealing properties and mechanical strength.

　　Insulating Bushings: These are used to lead the outgoing lines of the transformer windings from inside the oil tank to the outside while ensuring insulation between the outgoing lines and the oil tank. Insulating bushings are typically composed of porcelain bushings, conductive rods, and flanges, and have high electrical insulation performance and mechanical strength.

　　Cooling Devices: Common ones include radiators and cooling fans. Radiators increase the heat dissipation area and use natural convection and radiation to dissipate the heat of the transformer oil into the surrounding air. Cooling fans can accelerate air flow, improving heat dissipation efficiency, and are suitable for situations with high loads or high ambient temperatures.

　　Oil Conservator: Also known as an oil pillow, it is located above the oil tank and connected to the tank through a connecting pipe. The oil conservator regulates the volume changes of the transformer oil. When the oil expands due to heating, the excess oil flows into the conservator; when the oil contracts due to cooling, the oil in the conservator is replenished into the tank, ensuring that the tank is always full of oil and reducing the contact area between the oil and air to prevent oil oxidation and deterioration.

　　Buchholz Relay: Installed on the connecting pipe between the oil tank and the oil conservator, it is an important protection device for internal faults of the transformer. When an internal fault occurs in the transformer, gas is generated. The Buchholz relay detects the accumulation and flow rate changes of the gas, thereby issuing an alarm signal or a trip signal to protect the transformer's safety.

　　Technical Characteristics

　　High Insulation Performance: By using high-quality insulating materials and advanced insulation processes, combined with the insulating effect of transformer oil, it can withstand high voltages of 35kV and below, ensuring good insulation performance during normal operation and under overvoltage conditions.

　　Good Heat Dissipation Performance: Through reasonable cooling device design and the circulation of transformer oil, it can effectively dissipate the heat generated during the transformer's operation, ensuring that the transformer operates within the specified temperature rise range and improving its service life and reliability.

　　Strong Overload Capacity: It is designed with a certain overload capacity, allowing it to withstand operation above the rated load for a short period to cope with sudden power demands. However, the overload operation time should not be too long; otherwise, it will affect the transformer's lifespan and performance.

　　Stable Operation: It has stable voltage regulation and frequency response characteristics, capable of maintaining a stable output voltage under different load conditions and providing reliable power supply for electrical equipment.

　　Application Scenarios

　　Urban Power Grids: In urban power distribution systems, 35kV oil-immersed transformers are commonly used to step down 35kV high-voltage electrical energy and distribute it to various substations or user ends, meeting the power needs of urban residents and commercial users.

　　Industrial Sector: Widely applied in various industrial enterprises, such as steel plants, chemical plants, and cement plants. These enterprises usually require a large amount of power supply. The 35kV oil-immersed transformer can convert high-voltage electrical energy into voltages suitable for the production equipment of the enterprises, ensuring the normal operation of production.

　　Rural Power Grids: In rural areas, 35kV oil-immersed transformers are used to improve rural power supply conditions, stepping down 35kV high-voltage electrical energy and transmitting it to the rural power grid to provide power support for rural residents and agricultural production.

　　New Energy Power Generation: In fields such as wind power generation and photovoltaic power generation, 35kV oil-immersed transformers can be used to step up or step down the electrical energy generated by the power generation equipment for better grid connection or to meet the needs of different electrical equipment.

　　Selection Considerations

　　Capacity Selection: Rationally select the transformer capacity based on the size of the electrical load and future development plans. Generally, the rated capacity of the transformer should be slightly larger than the total power of the load to ensure that the transformer will not be overloaded during normal operation, and some load growth space should also be considered.

　　Voltage Level: Ensure that the rated voltage of the transformer matches the voltage level of the power system, including the high-voltage side rated voltage (35kV) and the low-voltage side rated voltage (selected according to actual needs).

　　Insulation Level: Choose an appropriate insulation level based on the insulation requirements and operating environment of the power system. The insulation level includes parameters such as lightning impulse withstand voltage, switching impulse withstand voltage, and power-frequency withstand voltage.

　　Cooling Method: Select an appropriate cooling method based on factors such as the transformer's load conditions, ambient temperature, and installation location. Common cooling methods include natural oil circulation natural cooling (ONAN), natural oil circulation forced air cooling (ONAF), and forced oil circulation forced air cooling (OFAF).

　　Losses and Efficiency: Pay attention to the no-load losses and load losses of the transformer, and choose a transformer with low losses and high efficiency to reduce operating costs and energy consumption.

　　Maintenance and Care

　　Regular Inspections: Regularly conduct visual inspections of the transformer, checking for oil leakage phenomena in components such as the oil tank, insulating bushings, and oil conservator. Inspect whether the cooling devices are operating normally and whether there are damages or blockages in fans, radiators, etc.

　　Oil Quality Testing: Regularly sample and test the transformer oil, analyzing its electrical, chemical, and physical properties, such as breakdown voltage, dielectric dissipation factor, moisture content, and acid value. Based on the test results, determine whether the transformer oil needs to be filtered, regenerated, or replaced.

　　Preventive Tests: Conduct regular preventive tests on the transformer in accordance with relevant standards and regulations, such as insulation resistance tests, DC resistance tests, turns ratio tests, and winding deformation tests. Through the test results, promptly discover potential fault hazards inside the transformer.

　　Temperature Monitoring: Install temperature monitoring devices to monitor the upper oil temperature and winding temperature of the transformer in real time. When the temperature exceeds the specified value, timely measures should be taken, such as strengthening cooling or reducing the load, to prevent transformer damage due to overheating.

　　Moisture and Dust Prevention: Keep the installation site of the transformer dry and clean to prevent moisture and dust from entering the transformer and affecting its insulation performance. In humid seasons or environments with high humidity, measures such as heating and dehumidification can be taken.