What Are the Types of Transformer Oil Tank?

A: Transformer Oil Tanks are mainly classified into several types based on structure and sealing performance: open-type oil tanks with conservators, fully sealed oil tanks, and corrugated oil tanks. Open-type oil tanks are equipped with conservators to compensate for oil volume changes caused by temperature fluctuations and reduce oil-air contact area. Fully sealed oil tanks adopt diaphragm or inflatable sealing structures, completely isolating oil from air, significantly improving oil aging resistance and suitable for harsh environments. Corrugated oil tanks use corrugated wall structures to achieve oil volume compensation through the elastic deformation of corrugations, eliminating the need for conservators and featuring compact size and good heat dissipation, widely used in 10kV distribution transformers. The selection of types depends on application scenarios, voltage levels, and environmental requirements.

A:   The main material of Transformer Oil Tanks is low-carbon steel plates, with thick steel plates used for large-capacity and high-voltage transformers to ensure mechanical strength, and thin steel plates or aluminum plates for small-capacity transformers to reduce weight. The selection criteria focus on three core points: first, mechanical performance, requiring sufficient tensile strength and impact resistance to withstand pressure changes and transportation impacts; second, corrosion resistance, requiring surface anti-corrosion treatment (such as spraying anti-rust paint) to adapt to outdoor, high-humidity, or coastal environments; third, welding performance, as the tank body is formed by welding, and the material must have good weldability to ensure sealing performance. For special environments such as chemical plants, stainless steel materials may be used to enhance corrosion resistance.

A: The key design requirements of Transformer Oil Tanks are specified in standards such as GB/T 6451 and IEC 60156, mainly including pressure resistance, sealing, mechanical strength, and heat dissipation. In terms of pressure resistance, corrugated oil tanks with a rating of 315kVA and below must withstand a 20kPa test pressure for 12 hours without leakage, while those above 400kVA require 15kPa. Sealed oil tanks filled with gas need to withstand 60kPa pressure for 12 hours. In mechanical strength, the tank body must withstand a 103kPa hydraulic positive pressure for 10 minutes without cracking. In heat dissipation design, the surface area of cooling structures (radiators, corrugated walls) must be calculated according to the transformer’s loss to ensure that the top oil temperature does not exceed the limit. Additionally, interface designs for accessories such as conservators, pressure release valves, and gas relays must be reserved.

A:  The sealing performance test of Transformer Oil Tanks mainly adopts the pressure test method, which is specified in DL/T 662-2010 and GB/T 6451. The specific process is: inject dry gas (such as nitrogen) into the tank body and apply a specified test pressure (different pressure values for different tank types). For example, general sealed transformers need to maintain 30kPa above normal pressure for 8-24 hours (longer for large-capacity transformers). During the test, check the entire tank body, welds, and flange connections for leakage using visual inspection or leak detection agents. For precision testing, helium leak detection can be used, which has high sensitivity and can detect micro-leaks. Qualified tanks must have no pressure drop and no leakage during the test.

A: The cooling structure of Transformer Oil Tanks (including radiators, corrugated walls, cooling pipes, etc.) is crucial for ensuring the transformer’s operating temperature. Its core role is to expand the heat dissipation surface area and accelerate the heat transfer from insulation oil to the external environment. For small transformers, natural convection cooling is adopted: the heated oil rises, and the cooled oil sinks to form a circulation, transferring heat through the tank wall or corrugated structure. For medium and large transformers, forced air cooling (adding fans to radiators) or forced oil circulation cooling (adding oil pumps) is used to improve heat dissipation efficiency. A reasonable cooling structure design can ensure that the transformer operates within the safe temperature range, avoid insulation aging caused by overheating, and extend the service life.

A: Common leakage causes include poor weld quality, aging or damage of sealing gaskets, deformation of flange connections, and corrosion perforation. Leakage detection methods are divided into traditional and advanced technologies: traditional methods include visual inspection (observing oil stains on the tank surface) and pressure test (judging leakage by pressure drop). Advanced methods include helium leak detection (using the high permeability of helium molecules to detect micro-leaks), infrared thermal imaging (finding abnormal temperature areas at sealed parts to infer leakage points), and acoustic detection (identifying leakage through high-frequency acoustic signals). In addition, oil quality analysis (detecting moisture and impurities in oil) can indirectly judge whether leakage causes external pollution.

A: Daily maintenance of Transformer Oil Tanks focuses on three aspects: first, regular inspection of the tank body and seals, including checking for oil stains, corrosion, and gasket aging, and replacing damaged seals in a timely manner; second, cleaning the cooling structure, removing dust, oil dirt, and debris on radiators or corrugated walls to ensure unobstructed heat dissipation; third, monitoring oil level and oil quality, observing the oil level gauge regularly to ensure it is within the normal range, and conducting regular oil quality tests (such as breakdown voltage, moisture content, and acid value) according to GB/T 7600 and IEC 60567 standards. For outdoor transformers, anti-corrosion maintenance (such as repainting) should be carried out regularly to enhance weather resistance.

A: The conservator is an important accessory of open-type Transformer Oil Tanks, located on the top of the tank body and connected to the tank through pipelines. Its core functions are twofold: first, volume compensation, which accommodates the volume expansion and contraction of insulation oil caused by temperature changes, avoiding excessive pressure or vacuum in the tank body and preventing damage to the tank or seals; second, reducing oil aging, as the oil level in the conservator is small, which reduces the contact area between insulation oil and air, thereby slowing down the oxidation and moisture absorption of the oil. Most conservators are equipped with breathers (desiccants such as silica gel) to further absorb moisture in the air and protect the oil quality.

A: The core difference between fully sealed and open-type Transformer Oil Tanks lies in the oil-air isolation method and structural design. Fully sealed oil tanks adopt diaphragm or inflatable seals, completely isolating insulation oil from air, which can effectively prevent oil oxidation and moisture absorption, and have a longer service life, but the manufacturing cost is higher. Open-type oil tanks use conservators for volume compensation, and the oil surface is in indirect contact with air, so the oil quality is more likely to deteriorate, requiring regular oil change maintenance, but the structure is simple, and the cost is low. In terms of application scenarios, fully sealed oil tanks are suitable for harsh environments such as high humidity and heavy pollution, while open-type oil tanks are widely used in general industrial and civilian power grids.

A: When an oil leakage accident occurs in a Transformer Oil Tank, the handling steps are: first, immediately cut off the power supply and stop the operation to prevent the leakage from expanding and causing fire or electric shock accidents; second, locate the leakage point through detection methods such as visual inspection and helium leak detection, and take temporary plugging measures (such as using sealing agents) for small leaks; third, for large leaks, drain the insulation oil in the tank, repair the leakage point (such as re-welding or replacing seals), and conduct a pressure seal test after repair to ensure no leakage; fourth, clean up the leaked oil and treat the contaminated area to meet environmental protection requirements according to DL/T 1004-2008 standards.

A: Common faults of Transformer Oil Tanks include oil leakage, tank deformation, corrosion, and blockage of cooling structures. For oil leakage, the solution is to locate the leakage point and repair or replace seals/welds. For tank deformation caused by excessive pressure or impact, it is necessary to check the mechanical strength, repair or replace the deformed parts, and re-conduct pressure tests. For corrosion, it is necessary to derust and repaint the corroded parts, and enhance anti-corrosion measures for serious corrosion. For blockage of cooling structures, the solution is to clean the radiators or corrugated walls to restore heat dissipation capacity. Regular preventive maintenance can effectively reduce the occurrence of these faults.