GNEE ELECTRIC Successfully Ships High-Efficiency S11-1250kVA/11/0.4KV Oil Immersed Transformer
May 21, 2026
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AtGNEE ELECTRIC , we recently completed the design, production, and shipment of a high-performance S11-1250kVA/11/0.4KV oil immersed transformer for an overseas power distribution project. The unit features all-copper windings, ultra-low losses, and a PEI of 99.61% – meeting the customer's strict energy efficiency requirements.
This shipment story highlights how GNEE ELECTRIC transforms customer challenges into tailored solutions.
Final product – the finished transformer ready for export packaging
Customer Inquiry and Initial Pain Points
The client, a power contractor in Southeast Asia, needed a 1250kVA three phase oil immersed transformer for an industrial park substation. Their key requirements were:
- Step-down from 11kV to 0.4KV
- Low losses to reduce long-term operating costs
- High efficiency (PEI ≥ 99.6%) to qualify for green building incentives
- All-copper windings for reliability and overload capacity
However, the customer faced two major pain points:
- Previous suppliers delivered units with aluminum windings (hidden specification) that overheated under peak loads.
- Long lead times (60+ days) delayed their project commissioning.
They needed a trustworthy manufacturer who could deliver a genuine S11-1250kVA/11/0.4KV oil immersed transformer with verified copper windings and fast turnaround.
Production Challenges and GNEE ELECTRIC's Custom Solution
Challenge 1 – Ensuring Authentic All-Copper Windings
The customer insisted on 100% copper winding verification. We provided:
- Raw material certificates for oxygen-free copper conductors
- In-process photos of HV and LV coil winding
- Third-party inspection (SGS) to confirm copper purity
Challenge 2 – Balancing Losses and Cost
The client wanted S11 loss levels but at a competitive price. Our engineers optimized the grain-oriented silicon steel core design and used high-permeability materials to achieve:
| Parameter | Achieved Value |
|---|---|
| No-load loss | 1.36 kW (compliant with S11) |
| Load loss | 12.0 kW |
| PEI | 99.61% |
Challenge 3 – Tight Delivery Schedule
The customer needed shipment within 30 days. Our standardized S11-1250kVA/11/0.4KV oil immersed transformer core components were already in stock. We fast-tracked assembly, performed full routine tests (IEC 60076), and completed production in 28 days.
Final Solution and Successful Shipment
The final 1250kVA oil immersed transformer delivered:
- All-copper windings (HV and LV)
- 11/0.4KV voltage ratio with Dyn11 vector group
- Dimensions: 1800×1560×1650 mm
- Weight: 3500 kg
- Accessories: Oil conservator, Buchholz relay, pressure release valve, Pt100 temperature sensor
After passing routine tests (insulation resistance, turns ratio, impedance, no-load loss, dielectric), the transformer was carefully packed in a fumigated wooden case and shipped via Tianjin port to the customer's site. The client confirmed receipt and praised our transparency and delivery speed.
This project demonstrates GNEE ELECTRIC 's ability to address customer pain points – hidden specifications, long lead times, and performance verification – by delivering a genuine S11-1250kVA/11/0.4KV oil immersed transformer with all-copper windings, ultra-low losses, and 99.61% PEI.
📞 Need a custom 0.4KV three phase oil immersed transformer for your project?
Contact GNEE ELECTRIC today for a fast quote, technical datasheet, and on-time delivery
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