1500kVA 11kV to 6.6kV S11 Oil Immersed Distribution Transformer for South Africa
This project features a 1500kVA S11-series oil-immersed distribution transformer engineered for South Africa. Designed for a specialized 11kV to 6.6kV step-down application, the unit utilizes a Delta-Star (Dyn11) vector group and premium copper windings. Manufactured by YEEG to rigorous IEC60076 standards, it delivers a zero-fault, low-loss power distribution solution tailored for regional grid stability.
Application
Industrial Infrastructure
Rated Voltage
11/6.6 kV
Rated Capacity
1500 kVA (1.5 MVA)
Transformer Type
Oil Immersed Distribution Transformer
Project Background
In 2025, YEEG delivered a specialized 1.5MVA power distribution solution to support energy infrastructure in South Africa. The project required a highly reliable transformer capable of stepping down 11kV medium voltage to a specific 6.6kV secondary voltage. The S11-series was selected for its advanced manufacturing technology and high-quality materials, ensuring a long operational lifespan under localized grid conditions.
Key Challenges
- Engineering the core and winding structure to perfectly accommodate the non-standard 11kV to 6.6kV step-down ratio while maintaining optimal impedance at 6.5%.
- Achieving strict energy efficiency targets by limiting no-load losses to 1.6kW and on-load losses to 16kW.
- Ensuring absolute compliance with IEC60076 standards to guarantee a zero-fault operational record in demanding environmental conditions.
Scope of Work
- Custom design and manufacturing of the S11-1500kVA-11/6.6kV oil-immersed distribution transformer.
- Integration of a No-Load Tap Changer (NLTC) providing a ±2*2.5% voltage regulation range on the primary side.
- Comprehensive factory testing and secure export packaging for containerized maritime transport to South Africa.
On-Site Gallery
Engineering Considerations
YEEG utilized pure copper for the winding material to maximize electrical conductivity and mechanical resilience. The transformer is configured with a Dyn11 vector group, utilizing a delta connection for high voltage and a star connection for low voltage. The ONAN cooling system and robust tank design are optimized to dissipate heat efficiently, maintaining dielectric integrity and extending the equipment's service life beyond standard expectations.
Project Outcome
The 1500kVA transformer was successfully delivered and commissioned in South Africa in 2020. It has maintained a flawless operational record with zero reported faults. The equipment continues to provide reliable and efficient power step-down performance, demonstrating YEEG's capability to deliver high-quality, long-lasting distribution solutions for international utility markets.
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