I. This oil-immersed transformer assembly line is designed for the manufacturing of 10kV, 35kV, and select 110kV oil-immersed distribution and power transformers. Centered around five core processes—core stacking, coil assembly, vacuum drying, vacuum oil filling, and final assembly & testing—it provides a fully customizable, non-standard automated production line. The entire line utilizes a modular unit combination system that can be flexibly configured according to workshop column grid dimensions, product capacity spectrum, single-shift production takt time, and existing overhead crane conditions. Whether for greenfield planning of a new oil-immersed transformer factory or automation upgrades to assembly and testing sections in traditional workshops, this solution serves as a technical foundation for engineering implementation.
The core of oil-immersed transformer manufacturing lies in the vacuum treatment of insulating oil and the drying quality of the active part (core-coil assembly). This process removes moisture from the assembled active part under high-temperature and high-vacuum conditions, followed by the injection of vacuum-degassed insulating oil to form an oil-paper composite insulation system. This directly determines the product’s dielectric strength, partial discharge level, and long-term operational lifespan. This assembly line upgrades this process from traditional discrete standalone operations to continuous automated production based on a roller conveyor backbone, minimizing the impact of manual handling on the cleanliness and sealing integrity of the active part.
II. Applicable Processes and Product Range
The production line employs vacuum drying and vacuum oil filling as its core process route. The typical production flow is as follows: Silicon steel sheets are sheared and stacked into cores; HV and LV coils are wound separately and undergo insulation treatment; coils are assembled onto core limbs, followed by active part wiring and clamping to form a complete active part; the active part is transferred into a vacuum drying tank for heating and vacuum drying to remove moisture from insulation materials; after drying, the active part is placed into the tank, which is then evacuated while vacuum-filtered, degassed, and dehydrated insulating oil is injected; after oil filling, seal leak testing is performed, and the transformer moves via roller conveyor to the testing station for routine tests including turns ratio, DC resistance, insulation resistance, withstand voltage, and partial discharge.
This process route applies to the manufacturing of:
- Oil-immersed distribution transformers (S11, S13, S20, S22 series energy-efficient types)
- Oil-immersed power transformers (35kV voltage class)
- Combined transformers for box-type substations
- Special oil-immersed transformers such as rectifier transformers and electric furnace transformers
III. Main Line Components
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Final Assembly & Roller Conveyor Zone
Powered or non-powered roller conveyors are laid out on the ground as the primary logistics carrier for the entire line. The roller line runs through assembly, oil filling, and testing stations, ensuring smooth ground-level transport of transformer tanks and finished products. Heavy-duty rollers are used, with diameter, spacing, and drive type customizable based on product weight. Auxiliary mechanisms such as pneumatic stoppers and lift-and-transfer units enable automatic diversion and positioning between processes. -
Lifting & Hoisting System
Overhead bridge cranes cover critical hoisting stations including core stacking, coil assembly, and active-part-into-tank operations. Crane rated load is customized to the maximum product weight, with dedicated lifting fixtures for vertical lifting and alignment of active parts. For large products, dual-hook synchronous lifting or turning devices can be configured. -
Vacuum Drying Unit
Comprises a vacuum drying tank (or drying oven), vacuum pump set, and heating system. Internal rails and carts accommodate the active part; after closing the door, the system evacuates and heats. The drying cycle controls vacuum level, temperature, and duration per preset curves to ensure thorough moisture evaporation and extraction from insulation materials. -
Vacuum Oil Filling System
Consists of a vacuum oil purifier, oil storage tank, vacuum pump set, and filling piping. Insulating oil undergoes degassing, dehydration, and precision filtration via the vacuum purifier before filling. During filling, a defined vacuum level is maintained inside the tank while oil is introduced from the bottom to prevent bubble formation. Filling speed, vacuum level, and settling time are programmable to ensure stable oil level without voids. -
Testing & Test Station
Electrical test stations at the end of the roller line integrate turns ratio testers, DC resistance testers, insulation resistance testers, and withstand voltage equipment. Transformers are conveyed to the test station, positioned, and locked; test probes connect automatically or manually to perform all routine electrical performance tests. Test data can be uploaded to the factory MES for archiving.
IV. Technical Specifications (Customizable)
All parameters above are reference values; all items are available as non-standard custom designs per customer requirements.
V. Key Points for Non-Standard Customization
This line has no fixed standard specifications; all parameters are adjustable per project needs:
- Facility Adaptation: Roller line length, layout, and height are customized to the workshop floor plan; crane span matches building column spacing; vacuum drying tank dimensions align with workshop door openings and foundation conditions.
- Product Adaptation: Roller line load capacity, crane rated load, and drying tank volume are sized to the customer’s maximum product weight and maximum active part dimensions.
- Capacity Adaptation: Throughput is matched by adjusting the number of drying tanks, oil filling stations, and test station parallelism.
- Operation Modes: Supports configurable combinations of manual, semi-automatic, and fully automatic modes to meet transitional needs at different stages.
VI. Process Quality Control
- Vacuum drying runs fully enclosed and automated, ensuring active part moisture content stays within specification.
- Insulating oil is filtered online under vacuum; vacuum level is maintained during filling to minimize residual bubbles.
- Roller conveying is smooth to avoid shock and collision during transfer.
- Test data is automatically collected and archived, enabling forward traceability for each unit.
VII. Application Value
Compared with traditional manual handling and standalone operations, this oil-immersed transformer assembly line integrates assembly, drying, oil filling, and testing into a continuous takt-based flow through coordinated roller conveyors and overhead cranes, reducing heavy-product manual transfers and inter-process waiting. Enclosed vacuum processing limits ambient humidity effects on insulation, helping stabilize electrical performance. The line is suitable both for new smart factories and for automation retrofits of assembly and testing sections in existing oil-immersed transformer manufacturing facilities.
