The power transformer oil tank is the core enclosure of an oil-immersed transformer. It houses the iron core and windings and is filled with transformer oil, ensuring that all active components are fully immersed. Transformer oil plays a critical role by providing both electrical insulation and effective heat dissipation, directly influencing transformer safety, efficiency, and service life.
For medium and large power transformers, the oil tank system is typically divided into two separate tanks. One tank contains the transformer main body, while the other is dedicated to the on-load tap changer. Since the tap changer produces electric arcs during operation, frequent switching would accelerate oil degradation and reduce insulation strength. A separate oil tank effectively isolates this impact, improving overall operational reliability and extending maintenance intervals.
Transformer Oil Tank Structure
Modern oil-immersed transformers commonly adopt a corrugated oil tank structure. This design consists of the main oil tank body combined with two long and two short corrugated steel plates installed externally. The corrugated plates are precisely formed using specialized corrugation production lines and assembled through gas-shielded welding processes.
The short corrugated plates feature right-angle edges on both sides, while the long corrugated plates are inserted into the inner side of these right-angle edges. This structural configuration simplifies welding between long and short plates, significantly improving welding efficiency and consistency. At the same time, it enhances sealing performance and effectively reduces oil leakage risks.
Transformers equipped with corrugated oil tanks benefit from compact overall dimensions, excellent heat dissipation capability, reduced material stress caused by oil expansion, and a clean, modern appearance suitable for both industrial and urban power distribution environments.
Types of Transformer Oil Tanks
Based on structural design and cooling performance, transformer oil tanks are generally divided into finned oil tanks and corrugated oil tanks.
Finned oil tanks are commonly used in models such as S11, SZ11, and SFZ11. Corrugated transformer oil tanks are widely applied in models including S9, S11, ZS11, and SHB11. The corrugated type is especially favored for its flexible expansion capability and superior natural cooling efficiency.
Applicable Transformer Range
Power transformer oil tanks are suitable for distribution and power transformers operating at voltage levels of 10kV and 35kV. The typical capacity range extends from 10kVA up to 8000kVA, covering most applications in industrial power systems, substations, renewable energy projects, and utility distribution networks.
Custom Manufacturing and Ordering Information
Transformer oil tanks can be manufactured strictly according to customer-provided drawings, ensuring full compatibility with existing transformer designs. In addition, customized design and fabrication services are available based on transformer capacity, voltage level, cooling requirements, and installation environment.
Power Transformer Oil Tank Features and Cooling Principle
Corrugated power transformer oil tanks operate in coordination with the transformer conservator. The oil level in the conservator is carefully controlled and should not be completely full. The oil tank and conservator are connected by an oil pipe, allowing automatic oil level adjustment during operation.
When oil volume inside the main tank decreases, oil flows from the conservator into the tank to maintain adequate insulation and cooling. Conversely, when transformer load increases and oil temperature rises, the expanding oil flows back into the conservator, preventing excessive internal pressure.
Inside the corrugated oil tank, the cooling oil circulates through vertically arranged cooling tubes. Temperature differences cause density variations in the oil, generating natural convection. This vertical convection path significantly improves heat dissipation efficiency without the need for external cooling equipment, making corrugated oil tanks an energy-efficient and low-maintenance solution for oil-immersed transformers.
Transformer Oil Tank Structure Diagram
Transformer Oil Tank Structure Diagram
Tank Rim-1
Corrugated Wall-2
Tank Bottom-3
Transformer oil tank dimensions
| Rated capacity (kVA) | Length | Number of pieces | Wavelength/Pitch | Height | Inner length × Inner width × Inner height | Base dimensions | Track gauge dimensions |
| 50 | 727 | 8 | 80 | 400 | 700×270×585 | 50×37×4.5Channel steel | 400×400 |
| 297 | 3 | ||||||
| 80 | 797 | 9 | 80 | 500 | 770×295×630 | 50×37×4.5Channel steel | 400×400 |
| 322 | 3 | ||||||
| 100 | 807 | 12 | 60 | 500 | 700×305×665 | 50×37×4.5Channel steel | 400×400 |
| 332 | 5 | ||||||
| 125 | 802 | 15 | 50 | 500 | 775×300×695 | 50×37×4.5Channel steel | 550×550 |
| 327 | 5 | ||||||
| 160 | 832 | 15 | 50 | 500 | 805×310×715 | 50×37×4.5Channel steel | 550×550 |
| 337 | 5 | ||||||
| 200 | 887 | 16 | 50 | 600 | 860×330×750 | 50×37×4.5Channel steel | 550×550 |
| 357 | 6 | ||||||
| 250 | 917 | 17 | 50 | 600 | 890×345×780 | 80×43×5Channel steel | 550×550 |
| 372 | 6 | ||||||
| 315 | 972 | 18 | 50 | 600 | 945×360×845 | 80×43×5Channel steel | 550×550 |
| 387 | 6 | ||||||
| 400 | 1017 | 19 | 50 | 600 | 990×375×885 | 80×43×5Channel steel | 550×550 |
| 402 | 7 | ||||||
| 500 | 1047 | 20 | 50 | 700 | 1020×390×925 | 80×43×5Channel steel | 660×660 |
| 417 | 7 | ||||||
| 630 | 1127 | 21 | 50 | 700 | 1100×420×970 | 80×43×5Channel steel | 820×820 |
| 447 | 8 | ||||||
| 800 | 1181 | 22 | 50 | 800 | 1150×440×1020 | 80×43×5Channel steel | 820×820 |
| 471 | 8 | ||||||
| 1000 | 1191 | 23 | 50 | 800 | 1160×450×1060 | 80×43×5Channel steel | 820×820 |
| 481 | 8 | ||||||
| 1250 | 1251 | 24 | 50 | 800 | 1220×465×1105 | 100×48×5.3Channel steel | 820×820 |
| 496 | 9 | ||||||
| 1600 | 1266 | 24 | 50 | 900 | 1235×470×1210 | 100×48×5.3Channel steel | 820×820 |
| 501 | 9 |
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