In the modern landscape of power distribution and electrical infrastructure, selecting the right transformer is critical for operational safety, efficiency, and long-term reliability. Among the various types of transformer available on the market, the dry-type transformer has emerged as a superior solution for applications where safety, environmental compliance, and minimal maintenance are paramount. Unlike traditional liquid-filled units, a dry type transformer uses air or solid insulation to cool its windings, eliminating the risk of oil leaks and fire hazards. Delong Electric Co., Ltd., a leading manufacturer based in China, has perfected the engineering of these units to deliver exceptional performance across a wide range of industrial and commercial settings. This article offers a comprehensive look at why Delong's dry-type transformers stand out, covering their design philosophy, technical prowess, and the real-world value they bring to businesses. Whether you are upgrading an existing facility or planning a new installation, understanding the capabilities of modern dry-type technology will help you make an informed investment.

The evolution of transformer design has been driven by the need for safer, cleaner, and more adaptable power solutions. Dry-type transformers address these demands directly by using materials like cast resin or vacuum-impregnated windings that are self-extinguishing and resistant to moisture. This design approach makes them ideal for indoor installations, crowded urban substations, and environments where any fluid leakage would be unacceptable. Delong Electric has invested heavily in research and development to optimize the thermal and dielectric performance of their dry-type units, ensuring they meet rigorous international benchmarks. Furthermore, the company’s commitment to customization means that each transformer can be tailored to specific voltage levels, power ratings, and installation constraints, providing a truly bespoke solution. As businesses around the world strive to reduce their environmental footprint and improve workplace safety, the dry-type transformer has become the default choice for forward-thinking engineers and facility managers.

A dry-type transformer is a static electrical device that transfers electrical energy between circuits through electromagnetic induction, using air or solid insulation instead of liquid oil. This fundamental design difference gives the dry type transformer distinct advantages in terms of safety, environmental impact, and operational simplicity. The windings are typically encapsulated in cast resin or impregnated with a special varnish that provides mechanical strength and electrical insulation, allowing the unit to withstand harsh conditions without the need for a liquid cooling medium. Because there is no oil, there is zero risk of leakage, contamination, or fire propagation, making these transformers acceptable even in sensitive areas like hospitals, data centers, and food processing plants. Additionally, the absence of oil dramatically reduces maintenance tasks such as oil sampling, filtration, and disposal, lowering the total cost of ownership over the equipment's lifespan. Modern dry-type transformers are designed to handle high voltage levels and power ratings comparable to their oil-filled counterparts, thanks to advances in insulation materials and thermal management techniques. This versatility has made them one of the most popular types of transformer for new installations worldwide, particularly in regions with strict fire safety regulations.

The working principle of a dry-type transformer is similar to that of any other transformer: an alternating current in the primary winding creates a changing magnetic field, which induces a voltage in the secondary winding. However, the critical difference lies in how the heat generated by electrical losses is dissipated. In a dry type transformer, heat is transferred from the windings to the surrounding air through natural convection or forced air cooling, often aided by strategically placed cooling ducts within the core and coil assembly. This thermal design must be carefully engineered to prevent hot spots that could degrade the insulation over time. Delong Electric uses advanced computer modeling and thermal simulation to optimize the distribution of heat, ensuring that every unit operates within its rated temperature class even under full load. The insulation system is typically Class F or Class H, allowing for high operating temperatures without compromising longevity. Moreover, the cast resin type transformer—a specific variant of dry-type technology—offers exceptional resistance to humidity, dust, and chemical vapors, making it suitable for harsh industrial environments. As energy efficiency standards become more stringent around the world, the dry-type transformer continues to evolve, with low-loss core materials and optimized winding configurations that minimize no-load and load losses.

The most compelling reason to choose a dry-type transformer from Delong Electric is the unparalleled safety profile it offers. Without any flammable insulating oil, the risk of fire is virtually eliminated, which is a crucial consideration for installations in buildings with high occupancy or sensitive equipment. Delong's transformers are constructed using flame-retardant materials that do not propagate fire, and they produce minimal smoke in the unlikely event of a fault, giving occupants more time to evacuate and reducing damage to adjacent assets. This inherent safety simplifies building code compliance and can even lower insurance premiums for facility owners. Beyond fire safety, the absence of oil means there is no possibility of ground or water contamination from leaks, making these transformers an environmentally responsible choice. Companies pursuing green building certifications such as LEED or BREEAM often prefer dry-type units because they support sustainability goals and reduce hazardous waste management requirements. Delong Electric reinforces this eco-friendly advantage by using recyclable materials in their transformer construction and implementing energy-efficient manufacturing processes.

Another major advantage is the dramatically reduced maintenance burden compared to liquid-filled alternatives. A dry type transformer does not require periodic oil testing, filtration, or replacement, nor does it need conservator tanks, Buchholz relays, or other oil-related accessories. The routine maintenance is limited to visual inspections, cleaning of air ducts and cooling surfaces, and checking electrical connections—tasks that can often be performed by in-house electrical staff without specialized training. This simplicity translates into significant cost savings over the transformer’s life, both in direct maintenance expenses and in reduced downtime. Delong Electric designs their dry-type units with easy access to connection points and cooling passages, making routine service quick and straightforward. Additionally, the robust cast resin encapsulation used in many of Delong’s models provides excellent protection against moisture ingress, salt spray, and industrial pollutants, extending the operational life even in challenging environments. For businesses operating in remote locations or with limited maintenance resources, the reliability and low upkeep of a dry type transformer is a decisive operational advantage.

Energy efficiency is a third pillar of Delong’s dry-type transformer offering. These units are built with high-grade grain-oriented silicon steel cores that exhibit low hysteresis and eddy current losses, resulting in excellent efficiency across a wide load range. The winding design uses high-conductivity copper or aluminum conductors arranged to minimize stray losses and optimize the magnetic flux path. Delong Electric provides detailed loss data and efficiency curves for each model, allowing customers to calculate the total cost of ownership and payback period accurately. Many of their transformers meet or exceed the efficiency levels specified by international standards such as the European Ecodesign Directive or the US Department of Energy regulations. By choosing a high-efficiency dry-type transformer, businesses can reduce their electricity bills significantly over the equipment’s lifetime, while also contributing to lower carbon emissions. This combination of safety, low maintenance, and energy efficiency makes Delong’s dry-type transformers a sound financial and environmental investment for any organization.

Delong Electric offers a comprehensive range of dry-type transformers with power ratings from small distribution units of a few kVA up to large power transformers exceeding 10 MVA, covering voltage classes up to 35 kV and beyond. The standard product line includes both cast resin type transformer designs and vacuum-pressure-impregnated (VPI) models, each suited to different application needs. Cast resin transformers provide excellent mechanical strength and environmental resistance, while VPI units offer a more economical solution for indoor applications with moderate humidity levels. All transformers are designed and tested in accordance with IEC 60076 11, the international standard specifically covering dry-type power transformers, ensuring consistent quality and performance. Delong also complies with other relevant standards such as ANSI/IEEE C57.12.01, GB/T 10228, and customer-specific specifications when required. The insulation levels, temperature rise limits, and sound levels are all carefully documented in the product datasheets, giving engineers the technical data they need to specify the right unit for their project.

Customization is a core strength of Delong Electric, allowing customers to tailor the transformer to their exact operational requirements. Options include custom voltage ratios, tap changers for voltage regulation, specialized winding configurations (Delta, Wye, or Zigzag), and enclosure types ranging from IP00 open construction to IP54 weatherproof enclosures for outdoor installation. For applications with harmonic loads, such as variable frequency drives or UPS systems, Delong can design transformers with K-factor ratings or special winding arrangements to handle additional heating. The company also offers a range of accessories, including thermistor or PT100 temperature sensors embedded in the windings, digital temperature controllers with alarm and trip functions, and enclosures with forced air cooling fans to increase the continuous power rating. The Customized service page on the Delong website provides detailed information about the pre-sales consulting, order fulfillment, and after-sales support process, including extended warranty options and installation guidance. This flexibility ensures that every dry type transformer is optimized for its specific application environment, delivering maximum performance and longevity.

Delong's engineering team uses advanced design software to perform finite element analysis (FEA) of the magnetic field, thermal distribution, and mechanical stresses within each transformer. This computational approach allows them to optimize the core and coil geometry for minimum losses and maximum reliability, while also ensuring that the unit can withstand short-circuit forces and lightning impulses. The manufacturing process includes precision winding machines, automated resin casting lines, and vacuum drying ovens that remove all moisture from the insulation system before encapsulation. Every transformer undergoes a comprehensive series of routine tests, including measurement of winding resistance, turns ratio, insulation resistance, partial discharge, induced overvoltage, and lightning impulse tests. For special projects, type tests such as temperature rise testing at full load are performed to validate the thermal design. This rigorous approach to design and quality control ensures that each Delong dry-type transformer meets the highest standards of performance and durability, giving customers complete confidence in their investment.

Dry-type transformers from Delong Electric are deployed across a diverse range of industries, each benefiting from the unique characteristics of this technology. In commercial buildings such as high-rise office towers, shopping malls, and hotels, dry-type units are installed inside the building footprint without requiring a separate transformer vault or fire suppression system. This saves valuable floor space and reduces construction costs, while also eliminating the environmental liability associated with oil-filled equipment. Hospitals and healthcare facilities rely on dry-type transformers for their critical power distribution because they provide a clean, safe power source that does not introduce any fire risk near patients, medical gas systems, or sensitive diagnostic equipment. Data centers—where downtime is measured in millions of dollars per minute—use dry-type transformers for their reliability, low maintenance needs, and ability to operate in close proximity to IT equipment without heat buildup issues. The marine and offshore industry also uses Delong's transformers on ships, oil platforms, and floating production units, where any oil leak would be catastrophic to the marine environment.

Industrial applications are equally extensive, encompassing factories, mining operations, chemical plants, and renewable energy installations. In manufacturing facilities, dry-type transformers power heavy machinery, robotic assembly lines, and process control systems while withstanding the dust, vibration, and temperature variations typical of industrial environments. The mining sector uses them for underground power distribution where oil-filled transformers would pose a serious fire and ventilation hazard. Chemical and petrochemical plants prefer dry-type units because they are impervious to corrosive gases and do not introduce any flammable liquid into the process area. Renewable energy projects, including solar farms and wind power plants, increasingly specify dry-type transformers for their collection and step-up applications because they require minimal maintenance in remote locations and perform reliably under variable load conditions. Each industry has unique electrical requirements, and Delong Electric's ability to provide tailored solutions—with the right voltage levels, power ratings, and enclosure types—makes them a trusted partner for project developers and engineering firms worldwide. The Product page on the Delong website showcases the full range of transformer solutions available for different sectors.

The versatility of the dry type transformer also makes it an excellent choice for utility and infrastructure projects. Municipal water and wastewater treatment plants use these transformers to power pumps, blowers, and control systems without the risk of oil contamination in the water supply. Railway and mass transit systems install them along tracks and in stations for traction power and auxiliary services, benefiting from their compact footprint and ability to operate in tunnels with limited ventilation. Even in the renewable energy sector, utility-scale battery storage systems and green hydrogen production facilities are turning to dry-type transformers for their low environmental impact and compatibility with advanced monitoring systems. Delong Electric's transformers are engineered to handle the dynamic loading patterns typical of these modern applications, with excellent overload capacity and fast recovery after fault conditions. As industries continue to electrify and decarbonize, the demand for safe, efficient, and reliable power distribution equipment will only grow, and Delong's dry-type transformers are well-positioned to meet that demand.

Quality assurance is the foundation of Delong Electric’s reputation, and every dry-type transformer is manufactured under a strict quality management system that is ISO 9001 certified. The company maintains a dedicated quality control team that oversees every stage of production, from incoming material inspection of core steel, copper windings, and resin compounds, to in-process checks during winding, assembly, and encapsulation. The final testing phase is particularly rigorous, with each unit undergoing a full suite of routine tests as specified by IEC 60076 11 and other applicable standards. These tests include measurement of no-load loss and current, load loss and impedance voltage, insulation resistance with a megohmmeter, dielectric tests including applied voltage and induced overvoltage, partial discharge measurement to ensure insulation integrity, and a lightning impulse test to verify the transformer’s ability to withstand surges. The test results are documented in a certified test report that accompanies every shipment, providing full traceability and accountability.

Beyond routine testing, Delong Electric invests in type tests and special tests to validate the design and performance of their transformer platforms. Temperature rise tests are conducted on representative units to confirm that the cooling system can maintain winding temperatures within the specified class limits under full load. Sound level measurements are taken in a semi-anechoic chamber to ensure that noise emissions meet the contractual limits, which is especially important for transformers installed in residential or commercial areas. Short-circuit withstand tests are performed at accredited laboratories to prove that the transformer can survive the mechanical and thermal stresses of a bolted fault on the secondary side. These type tests provide the engineering data needed to certify the transformer for use in critical installations such as hospitals, data centers, and industrial plants. Delong also holds product certifications from international bodies such as CE, UL, and SGS for various product lines, demonstrating compliance with global safety and performance standards. The About Us page on the company website provides an overview of the factory facilities, development history, and the professional team behind these quality achievements.

Environmental responsibility is also embedded in Delong’s quality framework. The company operates in compliance with the RoHS directive, ensuring that hazardous substances are restricted in their products and processes. The manufacturing plant implements waste reduction, recycling, and energy conservation programs to minimize its environmental footprint. Delong’s dry-type transformers are designed for recyclability at the end of their long service life, with the core steel, copper conductors, and aluminum components being easily recoverable through standard recycling channels. The company also provides documentation and support for customers who need to comply with local environmental regulations regarding electrical equipment. By combining rigorous quality assurance with a strong commitment to sustainability, Delong Electric delivers dry-type transformers that not only perform exceptionally well but also align with the environmental goals of modern businesses. This holistic approach to quality is a key reason why customers around the world choose Delong as their transformer partner.

Delong Electric Co., Ltd. brings over two decades of manufacturing experience to the table, with a proven track record of delivering thousands of transformers to customers across Asia, Europe, the Americas, Africa, and the Middle East. The company’s factory is equipped with state-of-the-art production machinery, including CNC winding machines, automated resin casting lines, and a comprehensive high-voltage testing laboratory. This infrastructure allows Delong to maintain consistent quality while offering competitive pricing through efficient manufacturing processes. The company’s engineering team is composed of senior electrical engineers and designers who have deep expertise in transformer technology, including specialized knowledge of dry-type, oil-immersed, and amorphous alloy designs. This multidisciplinary capability means that Delong can recommend the best type of transformer for any application, rather than pushing a single product line. Customers benefit from honest, expert advice that helps them make the right technical and commercial decision.

One of the most significant differentiators for Delong Electric is its focus on customization and customer service. Unlike large conglomerates that offer only standard catalog products, Delong actively works with clients to develop tailored solutions that meet unique performance requirements, space constraints, and budget parameters. The pre-sales process includes detailed technical consultation, load flow analysis, and preliminary design drawings, allowing the customer to see exactly what they are getting before placing an order. During production, the project manager provides regular updates on manufacturing progress and is available to answer any questions that arise. After delivery, Delong offers installation supervision, commissioning support, and a comprehensive warranty that covers material and workmanship defects. The Customized service page outlines the full range of after-sales support, including extended warranty options and a FAQ section that addresses common customer concerns. This commitment to the entire project lifecycle—from concept to commissioning—gives customers peace of mind and reduces the risk of costly delays or performance issues.

Global logistics is another area where Delong excels. The company has extensive experience in exporting transformers to over 50 countries, handling all aspects of international shipping, customs clearance, and documentation. Transformers are carefully packed for ocean freight using export-grade wooden crates with desiccant and shock indicators, ensuring they arrive in perfect condition. Delong can also arrange for door-to-door delivery, including inland transportation to the final installation site. The company’s News page regularly features updates about major export projects, such as the recent shipment of over 100 oil-immersed transformers to Central Asia, demonstrating their logistical capability and reliability. For urgent projects, Delong offers expedited manufacturing schedules and air freight options to meet tight deadlines. With a responsive sales team, a deep inventory of raw materials, and a flexible production facility, Delong Electric is well-equipped to serve both large-scale infrastructure projects and smaller specialized orders with the same level of professionalism and attention to detail.

Dry-type transformers represent the future of safe, sustainable, and efficient power distribution, and Delong Electric Co., Ltd. has positioned itself as a leading provider of these advanced electrical devices. From the inherent fire safety and environmental benefits to the low maintenance requirements and high energy efficiency, dry-type technology offers compelling advantages for a wide array of applications. Delong's commitment to quality is evident in every aspect of their operations—from rigorous adherence to international standards like IEC 60076 11, to the use of advanced simulation tools in design, and the thorough testing of every unit before shipment. The company's ability to deliver fully customized solutions, backed by responsive customer service and global logistics capabilities, makes them a reliable partner for businesses seeking a high-quality dry type transformer. Whether you are involved in a commercial building project, an industrial plant upgrade, or a renewable energy installation, choosing Delong Electric means choosing durability, efficiency, and peace of mind. We invite you to explore the full range of types of transformer available on the Home page, or contact our sales team to discuss your specific needs with one of our application engineers.

A dry-type transformer is an electrical device that transfers power between circuits using electromagnetic induction, with air or solid resin as the cooling and insulating medium instead of oil. It works by creating a changing magnetic field in the core that induces a voltage in the secondary winding. Because there is no oil, the unit is safer and requires less maintenance than liquid-filled alternatives. Delong Electric manufactures both cast resin and vacuum-impregnated dry-type transformers to suit different environments and performance needs. These transformers are widely used in indoor installations where fire safety is a priority.

The primary advantages of a dry-type transformer are superior fire safety, environmental friendliness, and lower maintenance requirements. Without oil, there is no risk of leaks, contamination, or fire propagation, making them suitable for indoor and sensitive locations. Dry-type units also eliminate the need for oil testing, filtration, and disposal, reducing operational costs. They are generally lighter and more compact than oil-filled transformers of the same rating. Delong Electric’s dry-type transformers offer these benefits while maintaining high efficiency and reliability.

Delong Electric designs and tests all dry-type transformers in accordance with IEC 60076 11, the international standard for dry-type power transformers. They also comply with other standards such as ANSI/IEEE C57.12.01, GB/T 10228, and customer-specific specifications when required. Each unit undergoes routine tests including insulation resistance, turns ratio, partial discharge, and lightning impulse tests. Type tests such as temperature rise and short-circuit withstand are conducted at accredited laboratories. The company holds ISO 9001 certification and product certifications including CE, UL, and SGS for applicable product lines.

Yes, Delong Electric specializes in providing customized solutions for dry-type transformers. They can tailor the voltage rating, power capacity, winding configuration, enclosure type, and accessories to meet your project requirements. Options include custom tap changers, K-factor ratings for harmonic loads, and specialized enclosures for outdoor or harsh environments. The company’s engineering team works closely with clients during the pre-sales phase to develop a design that fits the technical and budgetary constraints. More details are available on the Customized service page.

With proper installation and routine maintenance, a high-quality dry-type transformer from Delong Electric can operate reliably for 25 to 35 years or more. The lifespan depends on factors such as load profile, ambient temperature, humidity levels, and the quality of periodic inspections. Delong uses Class F or Class H insulation systems that withstand high operating temperatures without accelerated aging. The cast resin encapsulation provides excellent protection against moisture and contaminants. Regular cleaning of cooling ducts and checking of electrical connections will help maximize the service life.

Selecting the right power rating involves calculating the total connected load and applying appropriate demand factors and future growth allowances. Delong Electric’s sales engineers can assist with load flow analysis and transformer sizing based on your specific application. It is important to consider both the continuous load and any transient overload conditions that may occur. The transformer should be rated so that it operates within its nameplate capacity under normal conditions. Delong can also provide units with forced air cooling to increase the continuous rating when needed.

Yes, dry-type transformers can be installed outdoors when provided with a suitable weatherproof enclosure. Delong Electric offers enclosures with IP54 or higher ratings that protect against rain, dust, and humidity. The cast resin type transformer is particularly well-suited for outdoor use because the resin encapsulation resists moisture ingress and UV degradation. Outdoor units may include additional features such as anti-condensation heaters and stainless steel hardware. It is important to consult with Delong's engineering team to ensure the enclosure and cooling design meet the specific site conditions.

Routine maintenance for a dry-type transformer is minimal compared to oil-filled units. It typically involves periodic visual inspections for dust accumulation, signs of overheating, or loose connections. Cooling air ducts and fin surfaces should be cleaned to ensure proper airflow and heat dissipation. Electrical connections should be checked annually for tightness, and the insulation resistance should be measured as part of a preventive maintenance program. Delong Electric provides a detailed maintenance manual with each transformer, and their after-sales team can offer guidance on best practices.

The initial purchase cost of a dry-type transformer is generally higher than that of an equivalent oil-filled transformer, primarily due to the more expensive insulation materials and manufacturing processes. However, the total cost of ownership is often lower for dry-type units when factors such as installation, maintenance, insurance, and environmental compliance are considered. The elimination of oil containment structures, fire suppression systems, and routine oil maintenance can offset the higher upfront investment. Delong Electric offers competitive pricing and can provide a total cost analysis to help customers evaluate the economic trade-offs.

Detailed technical information, including product datasheets, test reports, and application guides, is available on the Product page of Delong Electric’s website. You can also contact the sales team directly for customized documentation and engineering support. The Home page provides an overview of the company’s product range and contact details. Additionally, the News page features case studies and project highlights that showcase real-world applications of Delong’s dry-type transformers. The company’s engineers are available for technical consultations and site visits to discuss your specific requirements in depth.