I. Project Overview and Technical Specifications for 105 Units of 11kV Three-Phase Oil-Immersed Distribution Transformers in Nigeria

This customized solution is developed by Hengfengshuai Electric for the urban and rural power grid upgrading and power supply renovation project across Nigeria. It delivers an integrated package consisting of 72 units of S11-3.15MVA transformers and 33 units of S11-3.75MVA 11/0.415kV oil-immersed distribution transformers. Having years of experience in exporting power transmission and transformation equipment to West Africa, Hengfengshuai Electric manufactures products in strict compliance with IEC 60076, GB 1094, Nigerian NIS and NESIS power codes, making them suitable for Nigeria’s tropical climate: high humidity, heavy rainfall and salt spray corrosion along the southern coastal areas; extreme high temperatures during dry seasons, Harmattan sandstorms and large diurnal temperature variations in the northern inland regions, as well as severe grid voltage fluctuations. All units are designed for Nigeria’s 50Hz standard power grid, covering the 11kV medium-voltage distribution network and 0.415kV low-voltage loads for industrial and civil use, and delivering stable power supply for urban power distribution, factory production and distributed photovoltaic grid connection.

The full product line adopts high-purity electrolytic copper windings with Dyn11 standard connection group and S11 low-loss energy-saving design. The oil-natural cooling mode enables outdoor open-air installation. Customized medium-voltage and low-voltage cable boxes are equipped, together with two low-voltage current transformers. The transformers feature high temperature resistance, high humidity resistance, salt spray protection and sand resistance, allowing uninterrupted long-term operation under Nigeria’s alternating dry and wet seasons while meeting the grid requirements of stable voltage regulation and low operation loss.

General Technical Parameter Table of Transformers

II. Advantages of Adopting Hengfengshuai Electric’s Customized 11/0.415kV Oil-Immersed Transformer Solution for Nigeria

Targeting pain points including Nigeria’s secondary 11kV-0.415kV distribution network, harsh tropical climate and severe voltage fluctuations in aging power grids, Hengfengshuai Electric provides a complete distribution transformer package of 72 units of 3.15MVA plus 33 units of 3.75MVA. Six core advantages make this solution ideal for West African power grid renovation, industrial park construction and photovoltaic supporting projects:

1. Batch supply of mixed-capacity transformers to match full-range urban and rural power distribution layouts Traditional projects purchase transformers of different capacities in separate batches, leading to scattered design, production and logistics cycles and higher civil supporting costs. Hengfengshuai Electric completes unified design, synchronous production and full-container sea transportation delivery for all 105 units:

   • The 3.15MVA model serves residential areas and small processing plants, while the 3.75MVA model caters to concentrated loads of large industrial parks and mining zones. Flexible capacity combination supports urban expansion across Nigeria.

   • Unified installation dimensions and interchangeable spare parts greatly reduce civil engineering and switchgear matching costs for substations and pole-mounted transformers, lowering the owner’s overall investment.

2. S11 low-loss copper-core design for 24-hour continuous operation and reduced grid power loss All units adopt high-magnetic-conductivity silicon steel sheets and full electrolytic copper windings. The energy efficiency indicators of the S11 series outperform conventional distribution transformers in West Africa:

   • Low no-load and load power losses suit year-round uninterrupted power supply in Nigeria. Mass deployment of these transformers can cut substantial power loss expenses annually, aligning with local power grid policies on loss reduction and efficiency improvement.

   • Copper windings resist high-temperature aging without abnormal overheating under full load at 45°C during dry seasons, suitable for unattended outdoor pole-mounted installation.

3. Unified 4.5% short-circuit impedance compliant with Nigeria’s power grid relay protection codes Both models feature a uniform 4.5% short-circuit impedance, fully meeting NESIS distribution network design standards:

   • Controllable short-circuit current mitigates impact on transformers caused by line faults.

   • Local power operation and maintenance staff do not need to recalculate protection parameters, significantly boosting commissioning efficiency for distribution switches and earthing protection and lowering local technical barriers.

4. Tropical all-region weather-resistant anti-corrosion design for both coastal salt spray and northern sandstorms Special upgrades are implemented to address Nigeria’s persistent high humidity in rainy seasons, Atlantic coastal salt spray, Harmattan sandstorms in northern inland areas and extreme high temperatures:

   • Tropical high-temperature resistant insulating oil and ethylene propylene diene monomer (EPDM) sealing parts for humid conditions prevent oil leakage and insulation dampness.

   • Multi-layer composite coating of epoxy zinc-rich primer and salt-spray/UV-resistant topcoat for oil tanks provides dustproof, salt-spray-proof and rain erosion resistance, applicable to both northern and southern regions.

   • ONAN natural cooling structure without fans eliminates sand jamming failures, fitting simple operation and maintenance requirements in remote rural areas.

5. Standard Dyn11 connection mitigates harmonic distortion from non-linear loads and improves low-voltage power quality The Dyn11 winding structure effectively offsets triple harmonics and resolves harmonic pollution generated by factory motors, photovoltaic inverters, welding machines and other equipment in Nigeria:

   • Reduces voltage distortion on the 0.415kV side to protect household appliances and industrial production equipment.

   • High-voltage delta and low-voltage star earthing architecture matches the mainstream earthing mode of Nigeria’s 11kV distribution network, delivering stronger stability under fault conditions.

6. Copper windings with strong short-circuit resistance to fit lightweight operation and maintenance modes in West Africa Winding ends are rigidly reinforced and pass short-circuit withstand tests per NIS standards:

   • Windings are less prone to deformation and damage under sudden grid short-circuits, drastically cutting maintenance frequency for field equipment.

   • Low no-load loss eliminates overheating risks under light loads, suitable for unattended distribution stations in rural Nigeria.

Supporting Successful Project Cases as Verification

With years of market presence in Nigeria, Hengfengshuai Electric has delivered the same S11 series distribution transformers for multiple benchmark projects, providing mature practical support for this bulk package of 105 units: Case 1: 42 Distribution Transformer Project for Textile Industrial Park in Lagos Free Trade Zone Hengfengshuai previously supplied 42 units of S11-3.15MVA/3.75MVA transformers of the same specification to support over 20 textile production lines in the park. Before renovation, aging aluminum-wound transformers in the park suffered severe salt spray corrosion during rainy seasons, leading to over 5 unplanned shutdowns monthly. Voltage fluctuations caused color deviation in printing and dyeing equipment and frequent production halts. After replacement with Hengfengshuai’s full-copper Dyn11 transformers, voltage fluctuations are stably controlled within ±3%, harmonic distortion rate drops by 70%, and the equipment operates continuously for 24 months in coastal salt spray conditions without oil leakage or insulation faults. The park’s comprehensive power loss cost is reduced by 16%, earning the supplier the annual Outstanding Equipment Vendor certification from the general contractor.
Case 2: 36-Unit Renovation Project for Rural Photovoltaic Microgrid in Kano State (Northern Nigeria) Northern inland Nigeria faces frequent Harmattan sandstorms and high temperatures in dry seasons. Traditional distribution transformers feature high power loss and heat dissipation channels blocked by sand. Hengfengshuai delivered customized anti-corrosion and dustproof S11 copper-core transformers to support a local 500kW photovoltaic microgrid. The unified 4.5% standardized impedance matches KEDCO grid protection parameters. The pole-mounted unattended equipment only requires a simple dust removal inspection once a year, completely resolving frequent power outages in rural areas and supplying power to residents across 8 surrounding villages. This project has become a model demonstration for northern Nigeria’s power grid renovation.
Case 3: 28-Unit Capacity Expansion Project for Oil & Gas Supporting Plant in Port Harcourt The Niger Delta coastal area features high humidity and heavy salt spray, while frequency converters and pumping units at oil & gas plants generate massive harmonics. Hengfengshuai’s Dyn11 winding transformers effectively suppress triple harmonics, and the unified short-circuit impedance simplifies on-site relay protection commissioning. The equipment passes a 720-hour salt spray aging test and runs at full load for 3 consecutive years without winding overheating or tank corrosion issues. Annual operation and maintenance costs are reduced by 40% compared with competing products.

III. Design & Development Phase of Tropical-Type 11kV Oil-Immersed Transformers for Nigeria

Combining Nigeria’s 11kV distribution network parameters, 45°C high ambient temperature, high humidity, salt spray, sandstorm conditions and NIS/NESIS standards, Hengfengshuai Electric’s technical team completes electromagnetic simulation to optimize silicon steel sheet proportions for S11 loss control, unify 4.5% short-circuit impedance, widen insulation creepage distance to suppress partial discharge in rainy seasons, and refine 3D drawings for iron core vibration reduction, double-layer anti-corrosion oil tanks and special sealing fittings for humid environments. A joint review is conducted by teams specializing in electromagnetism, process technology, quality inspection and West African overseas projects to verify voltage matching, weather-resistant structure, sea freight container dimensions, local grid access certification and on-site installation conditions. Mass production commences only after the review is approved.

IV. Production & Manufacturing Phase of 11kV Oil-Immersed Transformers for Nigeria

Hengfengshuai implements full-process quality control in compliance with ISO9001:

1. 100% full-item inspection for all incoming raw materials. Electrolytic copper, low-loss silicon steel sheets, humid-resistant insulation, tropical-grade transformer oil and sealing parts undergo accelerated high-temperature and salt spray tests, and are stored in constant-temperature dust-free warehouses.

2. Fully automatic cutting of iron cores with multi-stage stepped lamination to reduce noise and power loss; production flow proceeds only after measured loss indicators meet standards.

3. Dyn11 copper windings are wound in a Class 10,000 dust-free workshop with reserved oil cooling channels; DC resistance and turn ratio of each unit are tested piece by piece.

4. Multi-layer wrapping of insulation components followed by high-temperature deep vacuum dehydration to eliminate hidden risks of dampness during rainy seasons.

5. Hermetic welding of oil tanks with air tightness and leakage testing; multi-layer salt-spray-resistant anti-corrosion coating; double dustproof and waterproof sealing for flanges.

6. Assembly of iron cores and coils in dust-free workshops with silver brazing of leads; terminals designed to match Nigeria’s 0.415kV cable specifications.

7. Three-stage full vacuum drying of complete units to thoroughly remove moisture inside insulation materials.

8. Vacuum filling with tropical high-temperature resistant insulating oil and full pipeline reinforcement for sealing.

V. Factory Acceptance Test (FAT) Verification for Nigerian 11kV Oil-Immersed Transformers

All complete factory tests are carried out in strict accordance with IEC60076, GB1094, Nigerian NIS and NESIS standards. Dual-language English-Chinese test reports are issued before sea shipment:

1. Routine tests for every unit: winding DC resistance, transformation ratio and Dyn11 group verification, insulation resistance, power frequency withstand voltage, insulating oil testing, no-load/load loss measurement, 4.5% short-circuit impedance verification, and 45°C high-temperature simulated temperature rise test.

2. Additional type tests on prototypes: lightning impulse test, 720-hour salt spray aging test, alternating dry-wet cycle durability test, sandstorm simulation test, and dynamic & thermal stability test under sudden short-circuit. Shipment is authorized only when all indicators meet standards. Leveraging accumulated test data from previous projects in Lagos, Kano and Port Harcourt, test standards for this batch of 105 units are further optimized to adapt to differentiated working conditions across northern and southern Nigeria.

VI. Cross-Border Packaging & Transportation Phase of Nigerian 11kV Oil-Immersed Transformers

Hengfengshuai adopts split moisture-proof and dust-proof sealed packaging: bushings, temperature control accessories are individually packed in anti-rust wooden cases. All ports of transformer bodies are covered with sealing plates, and tanks are filled with dry nitrogen to resist moisture and salt spray during shipping. Heavy steel supports and thickened weatherproof tarpaulins are applied, with West Africa oversize shipping labels marked on tanks. English drawings, test reports, NIS certifications and spare parts lists are attached to each shipment. Logistics adopt a combined transport model of domestic highway, ocean shipping and inland road transportation within Nigeria. Customs clearance formalities and oversized road permits are processed in advance. Temperature and humidity impact recorders are installed throughout transit, with enhanced anti-salt-spray and anti-collision reinforcement for sea freight. Drawing on mature ocean shipping solutions from dozens of previous West African projects, synchronous on-time delivery of all 105 bulk units to the project site is guaranteed.

VII. On-Site Delivery, Installation & Commissioning (SAT) for Nigerian Oil-Immersed Transformers

1. Joint unpacking acceptance: Hengfengshuai overseas technical staff, the owner and local distribution supervisors jointly inspect appearance, nitrogen sealing and transportation records, and sign official acceptance documents.

2. Standardized installation for humid and salt-spray environments: Moisture-resistant sealant is supplemented on all flanges, and secondary vacuum oil filtration and exhaust are performed for complete units.

3. SAT on-site handover tests: Insulation, power loss, impedance and protection circuits are re-tested against FAT factory reports, generating test records recognized by local power authorities.

4. Multiple no-load closing impact tests followed by 24-hour stable trial operation, then graded load connection to Nigeria’s 11/0.415kV distribution network for official commissioning. Hengfengshuai overseas engineers possess on-site service experience across dozens of power distribution projects in Nigeria and can conduct parallel commissioning at multiple locations simultaneously, drastically shortening the full commissioning cycle of bulk equipment.

VIII. Full-Process Quality Control & Localized Operation and Maintenance Support

Six Dedicated Export Quality Control Nodes for West African Projects of Hengfengshuai

Closed-loop full-process control covering design, raw material warehousing, production processes, factory FAT testing, cross-border sea freight protection and on-site installation. Process images are archived for full traceability of quality, and non-compliant equipment is prohibited from factory delivery and commissioning. Weather resistance and anti-corrosion processes are continuously optimized based on accumulated quality control data from previous Nigerian bulk projects.

Localized Operation & Maintenance Services

Hengfengshuai provides complete English technical drawings, factory test reports, NIS certifications and tropical humid-climate specialized operation & maintenance manuals upon delivery. Specialized training is offered to local Nigerian maintenance staff, focusing on coastal salt spray anti-corrosion inspection, rainy season moisture-proof maintenance, northern sandstorm protection and daily maintenance of S11 low-loss equipment. Long-term spare parts supply is supported for local projects, following the mature service model proven in Lagos and Kano projects.

IX. Solution Summary

This complete package of 105 units (72 × 3.15MVA + 33 × 3.75MVA) of 11/0.415kV oil-immersed distribution transformers for Nigeria stands as a benchmark export project of Hengfengshuai Electric in West Africa. Equipped with specialized anti-corrosion and insulation designs for tropical high temperature, high humidity, salt spray and sandstorms, S11 full-copper low-loss windings, unified 4.5% impedance and Dyn11 harmonic suppression architecture, the transformers deliver one-stop solutions to core pain points of Nigeria’s urban and rural power grids, including unstable voltage, insulation dampness in rainy seasons, coastal corrosion, high grid power loss and industrial harmonic interference. The implementation of this solution is backed by accumulated technical and service experience from three proven successful projects: Lagos Industrial Park, Kano Photovoltaic Microgrid and Port Harcourt Oil & Gas Plant. Its capacity for bulk integrated delivery and adaptability to full-range working conditions across northern and southern Nigeria has been verified through long-term field operation.
Fully familiar with Nigeria’s NIS, NESIS, NERC grid access specifications as well as complete IEC and GB standards, Hengfengshuai Electric can customize complete oil-immersed distribution transformer solutions ranging from 10kV to 33kV with full capacity options to meet West African countries’ requirements on voltage levels, tropical climates and urban/rural/industrial load demands. The company supports power grid upgrading, industrial park power supply and photovoltaic new energy supporting construction across Nigeria. General contractors, power distribution companies and foreign trade clients are welcome to enquire and cooperate. Contact Email: hfs@hengfengshuai.com