Recently, a 2000kVA oil immersed transformer has been dispatched from VKE to a high-tech industrial park in South China. This "electric heart" will provide strong and reliable power support for a newly deployed automated assembly center within the park.
1. Core Stacking
High-grade cold-rolled silicon steel sheets (0.23~0.3mm thick) are stacked into a stepped cross-section to reduce eddy current losses.
Core laminations are bonded with epoxy resin glue and tightly strapped with steel bands. The no-load losses must comply with the GB/T 6451-2015 standard.
2. Winding
The low-voltage winding is made of flat copper wire, with a cross-sectional area designed based on a current density of 2.5 to 4 A/mm². While the high-voltage winding adopts a multi-layer cylindrical structure, with Nomex insulating paper between layers for isolation.
After winding, the coil undergoes constant-pressure drying (at a temperature of 110℃ ±5℃ for a duration of >=48 hours) to eliminate moisture.
3. Active Part Assembly
The core and windings are assembled together and secured with insulating spacers to ensure adequate main insulation distance (e.g., >=25mm for a 10kV transformer).
Tinned copper busbars are used for leads, and all welding points must be inspected by X-ray to ensure there are no air holes.
The tank body is constructed from Q235 steel plates (thickness >=6mm). Weld seams must pass kerosene penetration tests (no leakage).
The radiator features corrugated panels, with a heat dissipation area designed at 1.2-1.5m²/kW.
Before oil filling, evacuate the system to a pressure of <= 133 Pa and maintain this pressure for 4 hours to ensure that the water content of the insulating oil is <= 10 ppm.
After oil filling, the transformer is left to stand for 24 hours before undergoing the withstand voltage test (with a power frequency voltage of 35 kV for 1 minute).
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