EN
15MVA Cogeneration Plant
Project Overview
In Zambia, a private industrial developer commissioned a 15MVA cogeneration power plant to supply stable electricity for both manufacturing operations and surrounding communities—significantly boosting local energy self-sufficiency. The project demanded uninterrupted power delivery under extreme environmental and grid conditions, requiring transformers that could withstand high ambient temperatures, frequent voltage swings, and continuous full-load operation without failure.
Critical constraints included:
Extreme thermal stress: Ambient temperatures exceeding 40°C risking transformer overheating and derating
Unstable grid voltage: Frequent ±10% fluctuations requiring precise on-load regulation
Zero unplanned outages: Any shutdown would halt production and disrupt community supply
Full compliance with international standards: Equipment must meet IEC norms and be suitable for overseas installation and inspection
TSTY Electric’s Customized Solution
TSTY delivered a fully integrated, high-reliability oil-immersed transformer package engineered specifically for Zambia’s harsh tropical climate and mission-critical power environment—ensuring decades of stable, low-loss operation across all plant interfaces.
Core Technical Adaptations
Full copper windings for superior thermal conductivity and reduced load losses
Enhanced cooling system with oversized radiators and optimized oil flow paths to counteract high-temperature derating
High-altitude & high-temperature design validated per IEC 60076-7 (ambient up to 50°C, altitude >1,000m)
Hybrid tap-changing strategy: On-load (OLTC) and off-circuit (DETC) tap changers with 17-step precision for dynamic voltage stabilization across generator export, auxiliary, and grounding circuits
Equipment Scope Delivered
Equipment
Rating
Quantity
Key Features
Generator Step-Up Transformer
15 MVA, 11/34.5 kV
1 unit
• OLTC, 17 steps
• Full copper
• Oil-immersed
• IEC 60076 compliant
Station Auxiliary Transformer
4,000 kVA, 11/0.415 kV
2 units
• DETC, 17 steps
• Full copper
• Enhanced cooling
Low-Voltage Distribution
Transformer
2,500 kVA, 11/0.433 kV
1 unit
• OLTC, 17 steps
• Full copper
Grounding Transformer
62.5 kVA
1 unit
Full copper oil-immersed type
*All units passed third-party type testing per regional requirements prior to shipment.
Engineered for Africa, Validated Globally
While the tender called for standard oil-immersed transformers, successful deployment in Zambia’s demanding cogeneration environment required far more than catalog specifications. TSTY leveraged four proven capabilities to turn technical complexity into operational certainty:
Harsh-Environment Resilience
Our thermal design team modeled real-world Zambian summer conditions (45°C ambient, 24/7 load) to optimize radiator surface area and oil circulation—ensuring <65K temperature rise even during peak demand, well below IEC limits.
Precision Voltage Control Under Instability
By deploying both OLTC and DETC transformers strategically across the plant, we enabled automatic voltage correction at the generator export point while maintaining stable 0.4 kV auxiliary supply—critical for sensitive motor loads and control systems.
Global Standards, Local Readiness
Every transformer was built to IEC 60076 and shipped with bilingual (English/French) nameplates, test reports, and installation manuals—pre-approved by the client’s international engineering consultant to avoid customs or commissioning delays.
End-to-End Power System Integration
From generator step-up to grounding protection, our single-source solution eliminated interface risks between multiple vendors—delivering a unified, tested, and warrantied power conversion backbone that supports the plant’s 25-year operational life.
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