Transformer Manufacturer in China

XIAOPAI - Wenzhou Xiaopai Electric Power Technology Co., Ltd. - manufactures both the S9/10/11/13/20/22 35 kV sealed oil-immersed line and the SC(B)9/10/11/12/13 35 kV epoxy-resin cast dry-type line in Wenzhou, Zhejiang. "Manufacturer" is a word that gets borrowed a lot in China. A real transformer manufacturer runs the core lamination, the winding, the vacuum processing and the factory testing under its own roof. Here is what that looks like across the two lines.

1. THE CORE

Every transformer starts at the core. On the oil-immersed S9/10/11/13/20/22 line the core is made of high-permeability cold-rolled grain-oriented silicon steel with a step-lap lamination structure, and the core limb cross-section is a multi-step circular shape uniform with the yoke. On the dry-type SC(B)9/10/11/12/13 line the core uses imported cold-rolled silicon steel sheets with a step-lap joint, the limbs bound in Class F single-sided non-woven glass tape and the surface encapsulated in epoxy resin to reduce the no-load current and the core loss. A step-lap joint - rather than a straight butt joint - is a small manufacturing detail that lowers the losses and the noise.

2. THE WINDINGS

The windings are where a manufacturer's process becomes visible. The oil-immersed line adopts corrugated oil ducts with a non-impregnation process, binds the windings with shrinkable tape, and lays them as concentric coils with the high-voltage taps brought out in corresponding positions. The dry-type line fills the high-voltage winding with epoxy resin under vacuum casting, places DMD resin pre-impregnated fabric between the winding layers, and completes the coil by integral solidification molding. How the conductors are laid, insulated and supported is set out at Power Transformer Construction - Windings.

3. VACUUM PROCESSING - OIL AND RESIN

Moisture is the enemy of transformer insulation, so both lines end with a vacuum step. The oil-immersed line uses vacuum oil filling during the sealing process to remove moisture from the tank; the oil then covers the core and coils to an immersion depth of about 120 ± 10 mm, and units rated 1000 ~ 2000 kVA carry an outdoor signal thermometer. The dry-type line seals the windings in cast resin, which gives low partial discharge, low noise and excellent heat dissipation. Vacuum processing is what turns a clean assembly into a unit that survives decades in service.

4. FACTORY TESTS AND DOCUMENTS

XIAOPAI proves the build with tests, not with words. Each unit is issued a routine test report per the relevant IEC standard, and a type test report is available on request per model. The lines carry CE marking and are made under an ISO 9001 certified quality system, with factory acceptance testing before dispatch and third-party inspection available on request. The individual tests - ratio, load losses, dielectric withstand and the rest - are set out at 12 Transformer Factory Tests Briefly Explained.

5. TWO LINES, ONE PROCESS

XIAOPAI manufactures both families on the same five steps: core, winding, vacuum processing, testing and export documentation. The oil-immersed S9/10/11/13/20/22 line suits outdoor substations and utility networks; the dry-type SC(B)9/10/11/12/13 line suits indoor, urban and fire-sensitive sites. XIAOPAI is the manufacturer, supplier and system integrator for both, and the single contracting party for export documentation, quality monitoring and after-sales coordination. See the oil-immersed transformer page and the dry-type transformer page for the full specifications, quality checks and export notes.