Transformers
Oil Immersed Transformer
Experience robust and reliable power transformation with our Oil Immersed Transformers. Renowned for their exceptional cooling capabilities and high dielectric strength, these transformers are the workhorse of global power grids, from distribution substations to industrial facilities. Our Oil Immersed Transformers utilize high-grade mineral oil or alternative fluids, providing superior insulation and efficient heat dissipation for long-term operational stability. Available in a wide range of kVA ratings and voltage classes, they ensure minimal energy loss, precise voltage regulation, and robust overload capacity. Trust our compliant, durable oil-filled solutions for critical, high-performance power delivery.
44kV Oil Immersed Transformer
NPC ELECTRIC's 44kV Oil Immersed Transformer is a heavy-duty three-phase power unit tailored for efficient high-voltage to medium-voltage step-down in 50/60Hz AC grids, handling primary inputs up to 44kV (or 40-46kV variants). Built with a durable conservator-equipped tank and high-efficiency radiator system for optimal oil circulation and heat dissipation. Suitable for pole or pad-mounted installations with YNd11/Dyn1 vector groups and high BIL (200-250kV), it delivers precise 44kV to secondary levels (e.g., 11kV/13.8kV/0.69kV), optimizing power quality, reducing harmonic distortions, and facilitating seamless integration in expansive utility infrastructures.
450kVA Oil Immersed Transformer
The 450kVA Oil Immersed Transformer is a reliable three-phase distribution transformer engineered for medium-voltage step-down applications in 50/60Hz AC systems, typically with primary voltages of 11kV or 33kV (options for 6kV/10kV/20kV) and secondary at 0.4kV/0.415kV/0.433kV. High-grade cold-rolled grain-oriented silicon steel core with low-loss lamination reduces no-load losses, while copper or aluminum windings paired with premium mineral oil minimize load losses and enable ONAN cooling for strong overload capacity. Compliant with IEC 60076, GB/T6451, and energy efficiency standards (e.g., S11/S13 series), it achieves high overall efficiency (>98-99%) at typical loads, low noise (<55dB), and reduced total ownership costs for residential, commercial, and light industrial power distribution.
600kVA Oil Immersed Transformer
The 600kVA Oil Immersed Transformer is a robust three-phase distribution transformer designed for reliable medium-voltage power step-down in 50/60Hz AC networks, commonly with primary voltages of 11kV or 33kV. Utilizing premium grain-oriented silicon steel core (S11/S13 series) to achieve reduced no-load losses, copper or aluminum windings, and high-quality mineral oil , it minimizes load losses while providing ONAN cooling for substantial overload tolerance (up to 140% short-term). Compact design with Dyn11 vector group, BIL ratings, and pole/ground-mount flexibility ensures dependable performance, minimal energy dissipation, and seamless integration in modern distribution systems.
700kVA Oil Immersed Transformer
The 700kVA Oil Immersed Transformer is a high-performance three-phase distribution transformer optimized for dependable medium-voltage power conversion in 50/60Hz AC grids, featuring primary ratings of 11kV or 33kV and secondary at 0.4kV/0.415kV/0.433kV. It adopts a fully hermetically sealed corrugated tank construction for automatic volume compensation, delivering outstanding resistance to humidity ingress, corrosion. Incorporating low-loss grain-oriented silicon steel core (S11/S13 series compliant) for minimized no-load losses (typically 950-1300W), high-conductivity copper windings, and premium-grade mineral insulating oil (IEC 60296 certified, dielectric >55kV/2.5mm).
3000kVA Oil Immersed Transformer
The 3000kVA Oil Immersed Transformer is a high-capacity three-phase power distribution transformer engineered for heavy-duty medium- to high-voltage step-down. Premium high-permeability cold-rolled grain-oriented silicon steel core (S13/S18 series level) significantly reduces no-load losses (typically 3500–4800W), while high-conductivity copper windings and superior mineral or ester insulating oil (IEC 60296/IEC 61099 compliant, dielectric >60kV/2.5mm) achieve low load losses (around 22–28kW at 75°C), ONAN/ONAF cooling capability for sustained overloads (up to 150–180% short-term), noise levels <65dB, and peak efficiency >99%. Conforming to energy efficiency regulations, this transformer delivers substantial energy savings, reduced transmission losses, and dependable performance in industrial, utility, and renewable applications.
3150kVA Oil Immersed Transformer
3150kVA Oil Immersed Transformer is a high-capacity three-phase power transformer optimized for efficient voltage transformation in 50/60Hz AC medium-voltage networks, with primary ratings commonly at 11kV, 22kV, 33kV, or 35kV (adaptable to 10–38.5kV) and secondary at 0.4kV, 0.69kV, 6.3kV, 10kV, or 11kV. Employing advanced high-permeability grain-oriented silicon steel core (S13/S20 series compliant) for dramatically reduced no-load losses (typically 3200–5400W), high-purity copper windings, and premium insulating oil (IEC 60296 compliant, dielectric >60kV/2.5mm), it achieves low load losses (around 18–22kW at 75°C), strong overload capability (up to 150–180% short-duration), noise below 65dB, and efficiency exceeding 99%.This transformer minimizes operational expenses, transmission losses, and environmental impact in large-scale industrial, utility, and renewable setups.
4000kVA Oil Immersed Transformer
4000kVA Oil Immersed Transformer is designed for medium and large-scale power distribution systems that require high reliability, strong overload capacity, and long-term stable operation. The transformer adopts a fully sealed oil-immersed structure, effectively preventing moisture ingress and oil oxidation, thereby extending service life and reducing maintenance frequency. The transformer features excellent thermal performance and robust insulation strength, ensuring stable operation under continuous load or fluctuating grid conditions. Advanced oil circulation and cooling structure enhance heat dissipation, while precise manufacturing processes guarantee low noise and high mechanical strength.
5000kVA Oil Immersed Substation Transformer
The 5000kVA Oil Immersed Substation Transformer is engineered for high-capacity power substations that demand continuous stability, strong load adaptability, and long operational life. Featuring an advanced oil-immersed insulation system, the transformer effectively enhances dielectric strength and thermal conductivity, ensuring reliable performance under heavy and fluctuating load conditions. With superior short-circuit withstand capability and efficient cooling performance, the transformer provides dependable power conversion for substations serving industrial, commercial, and infrastructure applications.
150kVA Oil Immersed Transformer
NPC ELECTRIC's 150kVA Oil Immersed Transformer is a compact and efficient power distribution solution designed for low to medium load applications. Utilizing a traditional oil-immersed insulation system, the transformer delivers stable dielectric performance and effective heat dissipation, ensuring reliable operation under continuous service conditions. The optimized core and winding structure reduces energy loss while maintaining consistent voltage output, making it suitable for decentralized power networks. With low operating noise and dependable overload capability, the transformer supports stable power supply for residential, commercial, and light industrial users. Its compact footprint and proven oil-filled technology make it an economical and practical choice for localized power distribution systems.In-Depth Analysis
Oil-immersed transformers are built to deliver high efficiency, reliable performance, and advanced safety, helping businesses reduce energy costs while ensuring stable power supply. With future-ready adaptability for renewable energy and smart grid applications.
Comparative Analysis of Efficiency and Loss
Compared to the industry average, transformers exhibit lower losses and higher efficiency across the entire load range.
Load Efficiency Comparison(%)
No-load Loss Comparison(W)
High-efficiency Core Design
High magnetic permeability and low loss silicon steel sheets are used and processed by special process to reduce hysteresis loss and eddy current loss and improve conversion efficiency.
Improved Magnetic Permeability
+30%
Reduced Iron Loss
-35%
Multiple Protection Systems
IP65 protection grade design combines multiple protection measures such as anti-corrosion, anti-UV, anti-condensation and anti-small animal intrusion.
Waterproof Performance
IP65
Anti-Corrosion Ability
15 years+
Ultra-low Noise Technology
A special shock-absorbing structure, low-noise fans, and optimized heat dissipation design ensure operating noise is far below industry standards.
Noise Reduction
-15dB
Suitability for Residential Areas
Excellent
Intelligent Cooling System
The heat dissipation system with adaptive temperature control automatically adjusts the heat dissipation efficiency according to the load and ambient temperature to reduce energy consumption.
Heat Dissipation Efficiency
+40%
Temperature Stability
±2℃
Safety Wiring System
Insulated protective cover and anti-misoperation design ensure personnel safety during installation and maintenance and reduce accident risks
Insulation Grade
Class H
Safety Protection
IP2X
Intelligent Monitoring
An optional remote monitoring system is available to monitor operating status, temperature, load and other parameters in real time, and supports fault warning and remote diagnosis.
Data Collection Frequency
one times a minute
Fault Warning Accuracy
96%
Environmental Adaptability Analysis
Oil-immersed Transformers have been rigorously tested and can operate stably under various harsh environmental conditions.
Temperature Range
-40℃ ~ +55℃
Can work normally in extreme high and low temperature environments
Humidity Adaptation
0 ~ 100% RH
Including condensation environment, no frost requirement
Seismic Resistance Level
IEC 60068-2-57
Suitable for earthquake-prone areas
Altitude
≤3000m
More than special design
Why Choose Us
Discover why our Oil-immersed transformers are trusted worldwide for efficiency, safety, and reliability.
Oil-immersed Transformers Manufacturer
As a leading oil-immersed transformer manufacturer, NPC Electric specializes in designing and producing high-performance oil-immersed distribution transformers for power utilities, industrial facilities, and commercial networks. Our oil-immersed transformers are built with premium-grade materials and advanced insulation systems to ensure excellent cooling performance, high efficiency, and long service life.
We offer a full range of capacities and voltage ratings, including power transformers and substation transformers, customized to meet specific project requirements. Every unit is tested under strict IEC and ANSI standards to guarantee superior reliability, low noise, and minimal maintenance. Whether you need a standard oil-filled unit or a specialized design for challenging environments, NPC Electric delivers proven transformer solutions trusted worldwide.
We offer a full range of capacities and voltage ratings, including power transformers and substation transformers, customized to meet specific project requirements. Every unit is tested under strict IEC and ANSI standards to guarantee superior reliability, low noise, and minimal maintenance. Whether you need a standard oil-filled unit or a specialized design for challenging environments, NPC Electric delivers proven transformer solutions trusted worldwide.
Superior Cooling & High Overload Capability
Our Oil Immersed Transformers are engineered for superior cooling, which directly translates to high overload capability and extended operational life. The dielectric fluid (mineral oil or ester fluid) efficiently dissipates heat generated during operation, maintaining optimal internal temperatures even under demanding loads or high ambient conditions. This inherent cooling efficiency allows our oil-filled transformers to handle temporary overloads without compromising performance or integrity. By choosing our robust oil transformers, you ensure consistent, stable power delivery for your transmission and distribution networks, even during peak demand or unexpected surges, guaranteeing maximum uptime.
Exceptional Dielectric Strength & Reliability
Our Oil Immersed Transformers offer exceptional dielectric strength and unwavering reliability, essential for safeguarding your electrical infrastructure. The high-grade insulating oil acts as a formidable barrier against electrical breakdown, preventing flashovers and short circuits even under high voltage stress. This superior insulation capability, combined with our precision manufacturing, ensures consistent performance and minimal risk of failure over a very long operational lifespan. By deploying our reliable oil transformers, you invest in a proven technology that provides robust protection and a stable power supply for critical applications, from substations to industrial facilities.
Proven Durability & Extended Lifespan
Our Oil Immersed Transformers are synonymous with proven durability and an extended lifespan, making them a cost-effective long-term investment. The sealed tank design protects the active parts from atmospheric contamination (moisture, oxygen), which can degrade insulation over time. Combined with the self-healing properties of oil in case of minor faults, our transformers are built to endure harsh outdoor conditions and continuous heavy-duty operation for decades with minimal degradation. By selecting our durable oil-filled transformers, you ensure a resilient and low-maintenance component for your power grid, maximizing return on investment through unparalleled longevity.
Product Show
Explore the detailed design and practical application scenarios of oil-immersed transformers
37.5kV Oil-immersed Transformers
Transformer side structure
Oil-immersed Transformers Top Structure
Transformers Top Structure
Oil-immersed Transformer
transformer oil-immersed type
Oil-immersed Transformer Warning
Transformer Warning Notes
Oil-immersed Transformer Accessories
Accessories display instructions
33kv Oil-Immersed Low Loss Power Transformer
33kv Oil-Immersed Low Loss Power Transformer
75kV Oil-immersed Transformer
Transformer exterior design
Oil-immersed Transformer Internal Structure
Transformer Internal components
Testing and Certification
Tested with precision and certified to meet international standards as
well as strict industry requirements.
Bare Cable Test Report
SGS Inspection Report
Certificate of Acceptance
ISO Quality Certificate
ISO Environmental Certificate
ISO Occupational Certificate
UL Laboratory Certificate
UL Product Certificate
Project Cases
Distribution transformers have been successfully applied in many projects and have been highly praised by customers.
Jordan Smart Factory
CompletedProvide stable and reliable power conversion solutions for the smart factory to meet diverse production needs.
Country：Jordan
Model：75kVA Oil-immersed Transformer x 14
Colombia Ocean Park
CompletedEnsure the power safety of surrounding residents and meet daily work needs
Country：Colombia
Model：33kv Oil-immersed Transformer x 30
Chile Factory
Completed22kV Oil-immersed transformers provide safe, efficient, and reliable power distribution in Chile.
Country：Chile
Model：22kv Oil-immersed Transformers x 20
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
FAQ From Customers
-
What is an oil immersed transformer and how does it work?
An oil-immersed transformer is a type of distribution transformer that uses insulating oil for both cooling and electrical insulation. The oil absorbs heat from the transformer core and windings, then dissipates it through the tank walls or radiators. This process keeps the transformer efficient, stable, and protected from electrical stress, making it suitable for residential, commercial, and substation transformer applications. -
What are the advantages of using an oil immersed transformer?
Oil-immersed transformers provide excellent cooling performance, strong insulation, and long service life. Compared to dry-type transformers, they handle higher load capacities and operate more efficiently under continuous use. Their robust design makes them ideal for power distribution networks, substations, and industrial facilities where durability and reliability are essential. -
What types of oil immersed transformers are available?
Common oil-immersed transformer types include single-phase and three-phase oil-immersed transformers. A single-phase oil-immersed transformer is typically used for small-scale or residential applications, while a three-phase oil-immersed transformer is ideal for industrial and utility networks. There are also oil-immersed distribution transformers and substation transformers designed for different voltage and power ratings. -
How should oil immersed transformers be maintained?
Regular oil-immersed transformer maintenance ensures long-term reliability and safety. Routine tasks include checking oil level and quality, testing insulation resistance, monitoring temperature, and inspecting for leaks or unusual noise. The insulating oil in an oil-cooled transformer should be tested periodically to detect moisture or contamination, which can affect performance and insulation strength. -
What standards are followed in manufacturing oil immersed transformers?
All oil-immersed transformers manufactured by NPC Electric comply with international standards such as IEC, IEEE, and ANSI. Each unit undergoes strict transformer testing and quality control, including temperature rise, load loss, and dielectric strength tests. These standards ensure that every oil-immersed distribution transformer and substation transformer operates safely, efficiently, and reliably under demanding conditions.
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