8000kVA 120kV OLTC Power Transformer Exported to DR Congo — Full Project Case Study

Project Snapshot

Background: Power Infrastructure Demand in Central Africa

The Democratic Republic of Congo holds some of the most significant untapped energy resources on the African continent — yet its power infrastructure remains among the most underdeveloped relative to its economic potential. Large-scale power station projects, whether for grid expansion, industrial supply, or mining operations, require high-voltage transformer equipment capable of operating reliably in demanding tropical environments with limited local maintenance infrastructure.

For projects of this nature, equipment quality is not a negotiable variable. A transformer failure in a remote Central African installation does not mean a service call — it means months of downtime, expensive logistics for replacement equipment, and potentially significant contractual and operational consequences for the entire project.

The client for this project — a DRC-registered local company with deep operational experience in Central Africa — understood this reality well. Rather than simply issuing a purchase order and accepting delivery, they commissioned an independent quality inspection programme overseen by a highly experienced transformer industry veteran to verify that every aspect of the SZ13-8000/120 met the project’s requirements before leaving the factory.

Independent Quality Inspection: Industry Expert Oversight

What sets this project apart from a standard export transaction is the level of independent technical scrutiny applied at the factory stage.

The client engaged a former General Manager of Chint Electric’s transformer division — a professional with nearly two decades of experience building and running one of China’s leading transformer businesses — to personally oversee factory inspection and quality verification for this project. This individual had previously worked alongside the client on power infrastructure projects in Africa, and brought that combination of deep manufacturing knowledge and real-world African project experience to the inspection process.

During the factory acceptance testing period, our team also had the opportunity to exchange views with this industry veteran on the evolution of China’s transformer manufacturing sector and the dynamics of transformer exports to international markets — insights that come only from someone who has spent nearly twenty years at the centre of the industry.

For international buyers evaluating Chinese transformer suppliers, this kind of independent expert verification represents the highest level of third-party quality assurance available in the market. The fact that a former senior executive of a major Chinese transformer manufacturer chose to stake his professional reputation on this unit is, in our view, a meaningful endorsement.

Technical Specifications

The SZ13-8000/120 is a three-phase, outdoor-rated, oil-immersed power transformer with on-load tap-changing capability — designed for high-voltage power station and grid substation applications.

Core Nameplate Data:

Insulation Levels:

OLTC Tap Changer Voltage Settings (17-Position On-Load):

LV Side (Nominal):

10,500 V / 439.9 A

HV Neutral Point CT Data:

• Model: LRB-60
• Current Ratio: 150/5
• Terminals: S1-S3
• Quantity: 1

Compliance Standards:

GB1094.1/2-2013 · GB1094.3-2017 · GB/T6451-2023 · GB20052-2024

Oil Tank & Conservator Vacuum Tolerance:

98/20 kPa

Key Components in Detail

Preparing for Export: Nitrogen Filling and Pre-Shipment Configuration

Exporting a large oil-immersed power transformer to a destination thousands of kilometres away — and then onward to a landlocked Central African installation site — requires careful preparation of the unit for long-duration transport in challenging conditions.

For this export, the transformer was shipped in nitrogen-filled configuration — reducing transport weight from 22.9 tonnes (oil-filled) to 17.5 tonnes, while providing reliable protection for the internal insulation system against moisture during the extended sea voyage from China to East Africa.

The capsule-type conservator and the full complement of transformer oil were shipped separately alongside the main unit, ready for on-site installation and oil-filling upon arrival at the project location.

Complete Package: Switchgear Included

This project was not limited to the power transformer alone. Zhongxin General also supplied the associated switchgear as part of a complete power distribution package.

Supplying transformer and switchgear from a single source simplifies procurement, ensures technical compatibility between components, and reduces the coordination burden on the client’s project team — a practical advantage for projects in remote or challenging environments.

Factory Dispatch and Logistics

The transformer was manufactured and completed in July 2025, then held at the factory pending the client’s dispatch instruction. On September 16, 2025, the main tank departed the factory by heavy transport vehicle bound for the port.

Due to a logistics challenge encountered at the original port of loading — where the allocated vessel space proved insufficient for the transformer main tank’s dimensions — the shipment was rerouted. The main tank was redirected to Lianyungang Port, where appropriate heavy-lift vessel space was secured. By December 6, 2025, the transformer main tank had arrived at Lianyungang and was staged for loading.

This logistics episode — which added approximately two and a half months to the overall shipping timeline — is discussed in detail in our companion article: When Your Transformer Doesn’t Fit the Ship: A Real Story of Large Equipment Export Logistics →

Arrival and Verification: Mtwara Port, Tanzania

On February 4, 2026, the SZ13-8000/120 arrived at Mtwara Port, Tanzania — the transit point for onward delivery to the Democratic Republic of Congo installation site. The receiving logistics team conducted a full offloading and cross-checking inspection on arrival, verifying package condition, unit identity against documentation, and physical integrity after the sea voyage.

The inspection record confirmed: package condition — no damage. The unit arrived intact after a sea voyage of several weeks from Lianyungang, validating both the export packaging specification and the nitrogen transport preparation.

International Voltage Compatibility

The SZ13-8000/120 is built to China’s GB standard with a nominal HV voltage of 120kV. For international power station and substation projects, Zhongxin General manufactures equivalent OLTC power transformers to alternative voltage classes:

For African power infrastructure projects in particular, 132kV is the most common transmission voltage class across anglophone Sub-Saharan Africa. Contact our engineering team to discuss voltage class, insulation level, and any applicable local utility standards for your project.

Related Case Studies

31,500 kVA OLTC Transformer — Jingten Energy 35kV Substation, Xinjiang → Domestic OLTC delivery: dedicated industrial substation main transformer, manufactured and commissioned in 2026.

63 MVA/110 kV OLTC Transformer — Ningxia LNG & Helium Project → Our largest OLTC delivery to date: 150-tonne power transformer for a strategic Chinese LNG and helium production facility.

6,300 kVA Oil-Immersed Transformer — Xinjiang Data Center → Standard oil-immersed transformer for digital infrastructure: data center power distribution in Western China.

Exporting Dry-Type Transformers to Europe → CE certification, EU energy efficiency standards, and international FAT documentation — lessons from our first European export project.

About Zhongxin General Electric Energy Co., Ltd.

Zhongxin General is a Sichuan-based National “Little Giant” Enterprise manufacturing oil-immersed and dry-type power transformers, switchgear, prefabricated substations, energy storage systems, and EV charging infrastructure. Our transformer portfolio covers 30 kVA to 100 MVA, configurable to voltage classes including 6kV, 6.6kV, 10kV, 10.5kV,11kV, 15kV, 22kV, 33kV, 35kV, 69kV, 110kV, 120kV, and 132kV, in both GB and IEC/ANSI standard configurations for domestic and international projects.

Our products have been delivered to power infrastructure projects in Kazakhstan, the Democratic Republic of Congo, Tanzania, Argentina, Europe, and across China.

Enquire About Your Project

Whether you are developing a power station, industrial substation, or grid infrastructure project in Africa or internationally — and whether your network operates at 110kV, 115kV, 120kV, or 132kV — Zhongxin General’s engineering team can help you specify the right transformer and manage the export process from factory to site.

→ Contact Our Engineering Team → View Oil-Immersed Transformer Product Range → Browse All Case Studies

About the Author

Kevin Z

Kevin holds dual academic backgrounds in Electrical Engineering and English Language. He is a core member of two selective professional communities — a group of elite electrical engineers and a high-level ESL learning circle. With over 15 years of experience in international marketing and sales, Kevin currently serves as Director of International Trade at Zhongxin General.

Beyond his corporate role, Kevin is also a key member of a distinguished export business network based in Ningbo, Zhejiang — one of China’s most dynamic trade hubs. Through this circle of outstanding export enterprises, he gains deep exposure to best practices in business operations, management strategies, and global trade — insights he brings directly to his work and writing.