HENTG POWER 100kVA 11kV 0.4kV Oil Immersed Transformer Three Phase ONAN

1. Product Overview

The HENTG POWER 100kVA 11kV/0.4kV Three-Phase Oil-Immersed Distribution Transformer is a high-reliability, energy-efficient step-down power solution designed for the operational conditions of African utility networks and rural electrification projects. This unit steps down medium voltage from 11kV (with tapping options for 10kV, 11.5kV, or 13.8kV grids) to a stable low voltage of 400V/230V. It is suitable for residential communities, small commercial centers, agricultural processing, and mini-grid applications.

Manufactured with reference to IEC 60076 and IEEE C57 guidelines, this transformer features ONAN (Oil Natural Air Natural) cooling, a fully sealed corrugated tank, and sturdy internal construction. The design is intended to deliver consistent power quality while helping to manage operational costs and maintenance requirements in outdoor settings, including high-temperature and dust-heavy regions.

2. Key Selling Points

• Configured for 11kV African Grid Compatibility
  Engineered for integration with utility specifications common across Kenya, Nigeria, Tanzania, Uganda, and West African power networks. The primary voltage rating of 11kV aligns with the distribution voltage of numerous national grids. An optional off-circuit tapping feature (±2x2.5%) allows adjustment to accommodate 10kV, 10.5kV, or 11.5kV line variations.
• High-Efficiency Core & Low-Loss Performance
  The transformer utilizes grain-oriented silicon steel laminations and high-conductivity copper windings to achieve favorable no-load and load loss figures. This design assists in reducing technical losses and supports long-term operational savings over the equipment's service life.
• Hermetically Sealed Tank for Limited Maintenance
  Featuring a welded, corrugated steel tank with no conservator or breather, the transformer is sealed from external atmosphere. This ONAN hermetically sealed design removes the need for silica gel replacement and helps limit internal contamination from ambient moisture, dust, or salt—factors relevant to reliability in arid and coastal regions.
• Sturdy Outdoor Construction
  The transformer exterior is protected by a multi-layer epoxy primer and polyurethane finish, offering resistance to corrosion, UV exposure, and abrasive conditions. Internal insulation utilizes inhibited mineral oil (compliant with IEC 60296) to support effective heat transfer and dielectric performance.
• Protection & Monitoring Components
  Standard equipment includes a pressure relief device (PRD) , dial-type oil temperature indicator, Buchholz relay (gas and oil surge detection) , and drain/sampling valve. These components provide early indication of internal conditions, supporting predictive maintenance practices.

Detailed Technical Specifications

4. Addressing Sealing Performance in Dust-Prone Environments

Operational Consideration in Arid Regions:
In areas with significant airborne sand, laterite dust, and daily temperature fluctuations, sealing integrity is an important factor for transformer operation. Fine particulate matter can affect gasket surfaces over time, and normal oil volume changes during thermal cycling may stress standard seals. This can lead to oil seepage or internal contamination, potentially affecting dielectric performance and maintenance schedules.

Design Approach for Sealing Reliability:

• Hermetic Sealing (No Breather): The 100kVA unit uses a flexible corrugated tank wall that adjusts with oil volume changes. By removing the conventional silica gel breather, a common entry point for abrasive dust and moisture is eliminated.
• Reinforced Sealing System: Critical joints—including handhole covers, bushing turrets, and tap changer flanges—utilize Nitrile Butadiene Rubber (NBR) gaskets seated in machined grooves. This configuration supports even compression and helps resist gasket movement during transport on unpaved roads.
• Welding and Leak Testing: The tank body is constructed using continuous welding techniques and undergoes pressure testing before finishing. This helps verify the integrity of weld seams.
• Protective Coating System: The external surface receives a epoxy primer and polyurethane finish to help resist corrosion and abrasion, supporting the long-term condition of the sealed structure.

5. Frequently Asked Questions (FAQ) for African Distributors & EPC Companies

Q1: Is this transformer compatible with 11kV grid specifications used by utilities in Kenya or Nigeria?

A: Yes. The 11kV/0.4kV Dyn11 configuration is a widely used standard for distribution across East and West Africa. We can adjust parameters to align with specific utility requirements, including compliance with regional testing protocols. Certified type test reports and bushing adaptations are available upon request.

Q2: What is the estimated lead time for a container order of 100kVA transformers to Mombasa or Lagos?

A: For standard specification units (Copper winding, Dyn11, 11kV), the production and loading time is typically within 25-30 days to the port of loading. Shipping transit time to major African ports is additional. We provide standard export documentation support including Certificate of Origin, SONCAP (for Nigeria), PVoC (for Kenya/Tanzania), and Bill of Lading.

Q3: How does the transformer perform in elevated ambient temperatures (above 40°C)?

A: The ONAN cooling system and corrugated fin design are intended to support natural heat dissipation. For locations with sustained high ambient temperatures, an upgraded thermal class option (Class B/F insulation) is available upon request to help manage thermal stress.

Q4: What maintenance is suggested for this sealed unit in a dusty environment?

A: This is a low-maintenance design. Because there is no breather, silica gel replacement is not required. Suggested annual inspection includes: visual check of paint condition, verification of oil level, and functional test of the pressure relief device. Periodic Dissolved Gas Analysis (DGA) testing can be performed to monitor internal condition without opening the tank.

Q5: Is aluminum winding available as an alternative material option?

A: Yes. While Copper (Cu) windings are the common configuration for this unit, Aluminum (Al) windings can be provided to meet specific project budget considerations. Please note that this may result in slightly different dimensions and loss values. Our team can provide comparative information upon request.

Q6: Is technical guidance available for installation or commissioning on project sites?

A: Yes. HENTG POWER offers support options ranging from remote guidance during installation to on-site supervision by a technical specialist (subject to separate agreement terms). We aim to assist with proper installation and earthing practices.

6. Call to Action (CAT)

Request a Quote Today: Contact HENTG POWER for pricing information on the 100kVA 11kV/0.4kV Transformer, including shipping options and full technical datasheets.