I. Product Description
The Oil-Immersed Transformer is a classic power transformation device that utilizes insulating oil as the core insulation and cooling medium. It fully immerses the high-permeability silicon steel sheet core and copper winding within a sealed oil tank, facilitating heat transfer through natural convection of the insulating oil. This transformer is capable of converting high-voltage grid voltages such as 10kV and 35kV into the commonly used low voltage of 0.4V at the user side, covering a safe capacity range from 10kVA to tens of thousands of kVA. It is currently the most widely used distribution equipment in industrial and mining power grids, outdoor substations, and large-scale power transmission and distribution scenarios. The entire series complies with the national industry standard GB/T 1094.7-2024.
II. execution standard
GB1094.1~2-1996 Power Transformers
GB1094.3~5-2003 Power Transformers
GB1094.4-2005 Power Transformers
GB/T6451-2008 Technical Parameters and Requirements for Three-phase Oil-immersed Power Transformers
III. Product Features
Excellent heat dissipation performance: Relying on the strong thermal conductivity of insulating oil, combined with external cooling fins/pipes, it achieves efficient heat exchange, ensuring stable temperature control even during long-term full-load operation, and is suitable for high-load continuous power supply scenarios.
Longer service life: Insulating oil can isolate oxygen and moisture, providing comprehensive protection for the iron core and windings, significantly delaying the aging of internal insulating materials. Under normal operating conditions, the service life can reach over 30 years.
Lower operation and maintenance costs: With a mature and reliable structure, simple troubleshooting and component replacement processes, the procurement and maintenance costs over the entire life cycle are significantly lower than those of Dry-type Transformers of the same capacity, making it suitable for remote outdoor sites.
Outstanding overload capacity: The oil-cooled thermal buffer space is ample, capable of withstanding 1.2-1.5 times the rated load impact for a short period of time, perfectly adapting to power consumption scenarios with large seasonal fluctuations such as rural power grids and industrial plant areas.
Wide range of application scenarios: Supporting outdoor pole mounting and deployment in open-air substations, from ordinary urban and rural distribution networks to large power plant step-up stations, corresponding mature models can be found, with strong technical implementation coverage.
IV. Performance characteristics
Compared with the "8" series products, the S13 series products have a 14.88% reduction in no-load loss, a 10.47% reduction in load loss, and a 11.14% reduction in total loss. The energy-saving benefits are significant, and there are good social benefits.
| Model | Material | Size |
| S9/S11/S13 | Copper/Aluminum | 150*100*150cm |
At Jihui Electric Group Co., Ltd., we specialize in the research, development, manufacturing, and supply of medium and low voltage power transmission and distribution equipment up to 35kV. Our customized 10kV-35kV/0.4kV 30-2500kVA oil-immersed fully enclosed three-phase transformers are designed to provide safe, stable, and efficient power distribution solutions for industrial, commercial, renewable energy, and infrastructure applications.
As a professional Transformer Manufacturer, we understand that different projects require different electrical solutions. A transformer used in a factory may need high load capacity and continuous operation, while a transformer installed in an outdoor power distribution station may require stronger environmental protection and lower maintenance requirements.
For this reason, we provide customized transformer solutions instead of only standard products. Our Oil-Immersed Transformers can be designed according to different voltage levels, capacity requirements, installation conditions, and customer technical specifications.
The product range covers 10kV, 20kV, and 35kV medium voltage systems with low voltage output of 0.4kV. Available capacities range from 30kVA to 2500kVA, allowing our transformers to serve applications from small power distribution systems to large industrial projects.
With reliable oil insulation technology, fully enclosed tank structure, and three-phase transformer design, our products provide long-term stability for modern electrical networks.
A fully enclosed oil-immersed three-phase transformer is an electrical device that transfers electrical energy between different voltage levels through electromagnetic induction. It uses insulating oil as both an electrical insulation medium and a cooling medium.
The transformer receives electricity from a medium voltage network, such as a 10kV, 20kV, or 35kV power system, and converts it into a lower voltage level of 0.4kV for electrical equipment and end users.
The three-phase structure means the transformer contains three electrical phases working together. This design is widely used in industrial power distribution because it provides balanced power supply and efficient energy transmission.
The fully enclosed structure is one of the important features of this transformer. Unlike traditional open-type designs, the fully enclosed tank reduces exposure to external factors such as dust, moisture, and environmental contamination.
This structure helps improve reliability, reduce maintenance requirements, and support stable operation in outdoor and industrial environments.
A reliable transformer depends on the quality and cooperation of every internal component. At Jihui Electric, we focus on every detail during design and manufacturing to ensure stable performance.
The high voltage winding connects to the medium voltage power network. It receives electricity from the 10kV, 20kV, or 35kV system and transfers electrical energy through electromagnetic induction.
The winding design directly affects transformer efficiency and electrical safety. We carefully control insulation distance, winding arrangement, and manufacturing accuracy.
The low voltage winding provides 0.4kV output power for electrical equipment. It supplies electricity to factories, buildings, machines, and other low voltage applications.
The design of the low voltage winding focuses on stable current transmission and reliable operation under different load conditions.
The transformer core provides the magnetic path required for voltage conversion. A high-quality core helps reduce energy losses and improve transformer efficiency.
We use suitable electrical steel materials and optimized core structures to support reliable operation and lower unnecessary power consumption.
Transformer oil performs two important functions. First, it provides insulation between electrical components. Second, it transfers heat generated during operation.
The oil cooling system helps maintain proper operating temperatures and improves the service life of transformer components.
The fully enclosed tank protects internal components from external environmental influences. It helps reduce the impact of humidity, dust, and weather changes.
This design is especially suitable for outdoor substations, industrial areas, and locations requiring reliable long-term operation.
The operating principle of our oil-immersed transformer is based on electromagnetic induction. Although transformer technology involves electrical engineering, the basic concept is simple: the transformer changes voltage levels while transferring electrical energy.
When alternating current enters the high voltage winding, it creates a changing magnetic field inside the transformer core. This magnetic field induces voltage in the low voltage winding.
The ratio between the high voltage winding turns and low voltage winding turns determines the voltage conversion ratio.
For example, an electrical system with 10kV input voltage can be converted into 0.4kV output voltage through the transformer, allowing electrical equipment to operate safely.
During operation, electrical resistance and magnetic effects create heat. The transformer oil absorbs this heat and transfers it to the tank surface, where the heat is released into the surrounding environment.
This cooling method allows oil-immersed transformers to operate continuously while maintaining stable performance.
Our customized oil-immersed transformers cover a capacity range from 30kVA to 2500kVA. This wide range allows customers to select suitable transformer solutions according to actual power requirements.
Small capacity transformers are suitable for local distribution systems, while larger capacity models are designed for industrial plants, renewable energy projects, and large electrical networks.
Different countries and projects may use different voltage systems. Our transformer solutions support customization based on customer requirements.
Available voltage levels include 10kV, 20kV, and 35kV medium voltage systems with 0.4kV low voltage output.
This flexibility allows our transformers to adapt to different power distribution standards and project conditions.
The fully enclosed structure improves environmental adaptability. It helps protect internal components from moisture, dust, and external contamination.
This reduces maintenance requirements and improves operational reliability, especially for outdoor installations.
Heat control is important for transformer reliability. The oil cooling system effectively transfers heat away from internal components.
Efficient heat dissipation helps reduce thermal stress and supports longer transformer service life.
The insulation system directly affects transformer safety. Our transformers use reliable insulation materials and transformer oil to reduce electrical risks.
The insulation structure helps maintain stable performance during continuous operation.
A transformer is a long-term investment. Customers expect equipment that can operate reliably for many years.
Through optimized design, quality materials, and controlled manufacturing processes, our oil-immersed transformers provide durable performance and reduced maintenance requirements.
| Transformer Capacity | Typical Application | Main Advantage |
|---|---|---|
| 30-160kVA | Small commercial facilities, local power systems | Compact design and economical operation |
| 200-630kVA | Factories, workshops, industrial buildings | Balanced capacity and reliable performance |
| 800-2500kVA | Large industrial projects, substations, renewable energy | High power support and stable operation |
Source: Capacity application classification is based on common medium voltage transformer selection practices and industrial power distribution requirements.
At Jihui Electric, we focus on improving transformer performance through engineering design, material selection, and manufacturing control.
The transformer core directly influences energy efficiency. Our optimized core design helps reduce magnetic losses and improve operating efficiency.
According to customer requirements, we provide copper or aluminum winding options.
Copper winding provides excellent conductivity and strong electrical performance, while aluminum winding offers advantages in weight and cost efficiency.
Different projects may require different protection solutions. We can provide customized accessories and configurations according to application requirements.
During our years of experience in the power equipment industry, we have provided transformer solutions for many different applications. We know that each industry has different requirements for power stability, equipment reliability, installation conditions, and maintenance needs.
Our customized 10kV-35kV/0.4kV 30-2500kVA oil-immersed fully enclosed three-phase transformers are designed to meet the needs of various medium voltage power distribution systems. With flexible capacity options, reliable insulation performance, and strong environmental adaptability, these transformers are suitable for industrial, commercial, renewable energy, and infrastructure projects.
Modern factories depend on stable electricity to operate production lines, motors, automation equipment, and control systems. Any power interruption can affect production schedules and increase operating costs.
Our medium voltage oil-immersed transformers provide reliable voltage conversion from 10kV, 20kV, or 35kV power systems to 0.4kV low voltage systems used by industrial equipment.
They are widely applied in machinery manufacturing, automotive production, electronic manufacturing, metal processing, chemical plants, and industrial parks.
The rapid development of renewable energy has increased demand for reliable transformer equipment. Solar power stations, wind energy projects, and distributed energy systems require transformers that can operate efficiently under changing power conditions.
Our 10kV-35kV oil-immersed transformers help transfer generated electricity safely and efficiently between renewable energy systems and distribution networks.
The fully enclosed structure improves environmental protection and makes the transformer suitable for outdoor installation in renewable energy facilities.
Commercial buildings and public infrastructure require continuous electricity supply for daily operation. Shopping centers, office buildings, hospitals, transportation facilities, and public service projects all depend on reliable power distribution systems.
Our three-phase distribution transformers provide stable voltage conversion and flexible capacity options according to project requirements.
Mining and heavy industries often operate under demanding conditions, including dust, temperature changes, and continuous electrical loads.
The durable tank structure, reliable insulation system, and efficient cooling performance of our oil-immersed transformers make them suitable for challenging industrial environments.
Utility companies and electrical contractors require dependable transformer equipment for local distribution networks.
Our customized power transformers can be integrated into substations and distribution systems to support stable electricity supply for different users.
| Application Industry | Transformer Requirement | Product Advantage |
|---|---|---|
| Industrial Manufacturing | Continuous and stable power supply | Reliable operation with efficient cooling |
| Renewable Energy | Stable grid connection | Flexible voltage and capacity customization |
| Commercial Buildings | Safe and dependable electricity | Low maintenance fully enclosed structure |
| Mining and Heavy Industry | Strong environmental adaptability | Durable design and reliable insulation |
Source: Application information is based on common medium voltage transformer applications and industrial power distribution engineering practices.
At Jihui Electric, we believe that transformer reliability begins during manufacturing. Every step, from engineering design to final inspection, affects the performance and service life of the transformer.
Before production starts, our engineering team communicates with customers to confirm technical requirements, including voltage level, capacity, installation environment, frequency, protection requirements, and project standards.
For customized 10kV-35kV/0.4kV transformers, we adjust the design according to customer needs to ensure the final product matches the electrical system.
The transformer core is one of the most important components affecting energy efficiency and operating performance.
We select suitable electrical steel materials and use accurate processing methods to manufacture stable core structures.
A properly designed core helps reduce no-load losses, improve efficiency, and lower operating temperature.
The winding system directly affects transformer electrical performance. During manufacturing, we control winding arrangement, insulation distance, and mechanical strength.
Customers can choose copper or aluminum winding according to application requirements and project budgets.
After completing the core and winding production, our technicians assemble the transformer body, install internal components, and complete electrical connections.
The assembly process requires careful inspection to ensure mechanical strength and reliable operation.
Transformer oil provides insulation and cooling functions. During production, qualified insulating oil is filled into the transformer under controlled conditions.
The fully enclosed sealing structure helps prevent moisture and external contamination from entering the transformer.
This improves reliability and reduces maintenance requirements during long-term operation.
Before delivery, every transformer undergoes professional testing procedures.
We inspect electrical performance, insulation condition, structural quality, and appearance to ensure the transformer meets customer requirements.
| Inspection Stage | Main Testing Items | Purpose |
|---|---|---|
| Material Inspection | Core, winding, insulation oil | Ensure reliable raw materials |
| Production Inspection | Assembly accuracy and structure | Maintain manufacturing quality |
| Electrical Testing | Insulation, resistance, loss testing | Verify electrical performance |
| Final Inspection | Appearance and documents | Ensure safe delivery |
Source: Quality inspection procedures are based on transformer manufacturing practices and IEC 60076 series requirements.
Our transformer specifications can be customized according to project requirements. The following table shows typical parameters for our oil-immersed fully enclosed three-phase transformers.
| Parameter | Typical Specification |
|---|---|
| Transformer Type | Oil-immersed Fully Enclosed Three-phase Transformer |
| Rated Voltage | 10kV / 20kV / 35kV to 0.4kV |
| Capacity Range | 30kVA-2500kVA |
| Phase | Three Phase |
| Winding Material | Copper / Aluminum (Cu/Al) |
| Cooling Method | Oil Natural Air Natural (ONAN) |
| Structure | Fully Enclosed Tank Design |
Source: Typical technical specifications are based on common medium voltage distribution transformer configurations.
Choosing a transformer supplier is not only about purchasing equipment. It is about selecting a partner who understands electrical systems and can provide reliable long-term support.
Jihui Electric Group Co., Ltd. specializes in medium and low voltage power transmission and distribution equipment up to 35kV.
Our product range includes oil-immersed transformers, Dry-type Transformers, Cable accessories, Cable distribution boxes, ring main units, Prefabricated Substations, combination transformers, SF6 load switches, and Vacuum circuit breakers.
With complete product categories, we can provide integrated solutions for different power distribution projects.
We operate according to strict quality management systems and have obtained ISO9001 quality management certification, ISO14001 environmental management certification, and ISO45001 occupational health and safety management certification.
These certifications reflect our commitment to stable manufacturing, responsible production, and continuous improvement.
Different projects require different transformer solutions. We support customization based on:
Voltage level requirements
Capacity selection from 30kVA to 2500kVA
Copper or aluminum winding options
Protection accessories
Installation environment
Special project requirements
For overseas customers, we provide complete export services including technical communication, production scheduling, inspection support, packaging, and transportation arrangement.
According to transformer size, quantity, and destination, we select suitable transportation methods such as sea freight, land transportation, or combined logistics.
Professional protective packaging is used to prevent moisture, vibration, and impact during transportation.
It is used to convert medium voltage electricity from 10kV, 20kV, or 35kV networks into 0.4kV low voltage power for factories, buildings, renewable energy systems, and industrial equipment.
A fully enclosed structure improves protection against moisture, dust, and environmental influences, reducing maintenance requirements and improving reliability.
Yes. We provide customized solutions from 30kVA to 2500kVA according to customer power requirements.
Yes. We support both copper and aluminum winding solutions based on project requirements.
We ensure quality through material inspection, controlled manufacturing processes, electrical testing, and final inspection before shipment.
At Jihui Electric Group Co., Ltd., we are committed to providing safe, reliable, and efficient power distribution solutions for customers worldwide.
Our customized 10kV-35kV/0.4kV 30-2500kVA oil-immersed fully enclosed three-phase transformers combine flexible design, reliable performance, and professional manufacturing capability.
With advanced production technology, strict quality control, and international service experience, we help customers build safer and more efficient electrical systems.
If you are looking for a customized oil-immersed transformer manufacturer or need a 10kV-35kV three-phase transformer solution, Jihui Electric is ready to provide professional products and technical support for your project.
JiHui Electric Group Co., Ltd , high-end website construction, foreign trade website construction, marketing website construction, website optimization, development websites, corporate network marketing, search engine promotion, wechat mini program, corporate mailbox, short video operation, etc.
No. 161 Jingliu Road, Yueqing Economic Development Zone, Yueqing City, Zhejiang Province, China
jh.power@jihuielec.com
+86 18967711966
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