Innovative Technology of Site Assembly Transformer: Overcoming Transportation Challenges for Large Power Transformers

Unlike original SAT approaches, this new technology expands the applicable range by integrating regional expertise with advanced global design, manufacturing, and quality assurance practices. Three main areas of technological development have been emphasized: (1) addressing unique market and regional requirements, (2) ensuring reliable disassembly and reassembly through robust design and manufacturing quality, and (3) optimizing transportation design to satisfy strict logistical constraints. Advanced transformer engineering know-how and state-of-the-art simulation tools have been applied to solve key magnetic, dielectric, thermal, and mechanical challenges.

A central innovation is the yoke-split structure, where the bottom yoke is divided between the core limbs. This enables limb-by-limb transportation and facilitates on-site core reassembly by allowing shorter reassembling period and less instrument for reassembly by reinserting the core laminations into the bottom yoke. The effectiveness of these innovations was validated through a full-scale pilot project with a 525 kV, 250 MVA single-phase transformer (equivalent to 750

MVA in three-phase configuration). The transformer underwent comprehensive factory acceptance tests (FAT) before and after disassembly and reassembly, using identical test parameters. It also passed transportation tests under extreme conditions, demonstrating the robustness of the products.

All active components—including the core, windings, cleat, leads, insulation duct structures, tap changer, and bushings—were specifically designed for ease of disassembly, safe transportation, and reliable reassembly. Special transport tanks were developed for both winding packages and individual core limbs, ensuring safe and efficient logistics. The design, manufacturing, and quality assurance of the SAT pilot transformer were thoroughly validated through controlled production processes and quality checks, including two complete rounds of full-scale FAT and transportation tests.

The initial FAT confirmed that the pilot transformer met all performance specifications required for deployment. Transportation tests demonstrated the unit’s ability to withstand harsh conditions without damage or deformation. A second FAT, conducted after disassembly, transport, and reassembly, showed no deviation from initial performance, confirming that structural integrity and functional quality were consistently maintained.

The successful validation of this innovative SAT technology with a 500 kV-class pilot transformer demonstrates its applicability across a wide range of voltage and power ratings.

This technology provides complex solutions to the most challenging logistical problems, enabling installations in both densely populated urban areas and remote locations with difficult access. Integrating regional expertise and global design with advanced simulations and engineering solutions evaluated and validated customized transformer designs tailored to specific site and transportation constraints, enabling the innovative SAT technology. The innovative SAT technology allows for customized transformer designs tailored to specific site and transportation constraints, evaluated and validated using advanced simulations and engineering solutions. The resulting optimized solutions meet the technical performance standards of original transformers, as demonstrated by the pilot transformer.