Guizhou Delong Electric Co., Ltd. has established itself as a premier manufacturer in the electrical equipment industry, particularly known for its high-performance dry transformer solutions that serve clients around the world. The company’s unwavering commitment to safety, reliability, and continuous innovation has made it a trusted partner for businesses across commercial, industrial, and utility sectors. When it comes to power distribution, selecting the right transformer is a critical decision that affects operational efficiency, regulatory compliance, and long-term capital expenditure. This comprehensive guide explores everything you need to know about dry type transformers, from fundamental principles to detailed selection criteria, so that you can make a fully informed purchasing decision. By understanding the unique advantages of dry type technology and how Guizhou Delong’s products excel in each area, you will be equipped to optimize your electrical infrastructure for maximum performance and minimal risk. We invite you to visit ourHome page to learn more about our company’s mission, engineering capabilities, and global footprint in the transformer industry.

A dry type transformer is an electrical device that transfers energy between circuits through electromagnetic induction without using any liquid coolant such as mineral oil or synthetic ester fluids. Instead of oil, these transformers rely on air as the primary cooling medium and employ solid insulation materials like epoxy resin or reinforced varnish to provide electrical isolation between windings and ground. The term dry transformer specifically refers to this absence of liquid, which brings numerous advantages in terms of operational safety, environmental protection, and installation flexibility. Dry type transformers are widely used in applications where fire safety is paramount, including commercial high-rises, healthcare facilities, data centers, and enclosed industrial zones. Unlike their oil-immersed counterparts, dry type units eliminate the risk of oil leaks, fire spread, and soil contamination, making them the preferred choice for indoor and environmentally sensitive locations. Furthermore, they simplify routine maintenance since there is no need to monitor oil levels, test dielectric fluid, or manage disposal of hazardous waste at end of life.

The operating principle of a dry type transformer is rooted in Faraday’s Law of electromagnetic induction, which describes how a changing magnetic field induces voltage in a conductor that cuts across the flux lines. When alternating current flows through the primary winding, it generates a magnetic field in the laminated silicon steel core that continuously fluctuates in magnitude and direction. This varying magnetic field then links with the secondary winding, inducing a voltage that drives current through the connected load and thus completes the power transfer. The voltage transformation ratio is determined by the turns ratio of the primary winding to the secondary winding, allowing engineers to step voltage up for long-distance transmission or step it down for safe utilization. In dry type transformers, the heat generated by core losses and copper losses is dissipated through natural convection or forced air circulation, ensuring that winding temperatures remain within the rated limits of the insulation system. The air-cooled design also contributes to a compact, lightweight form factor that facilitates installation in spaces where oil-filled equipment would require expensive fire-rated vaults and containment measures.

When comparing dry type versus oil-immersed transformers, safety emerges as the most significant differentiator that influences equipment selection in modern power systems. Dry type transformers use non-flammable insulating materials such as epoxy resin or high-temperature varnish, which virtually eliminate the risk of fire even under severe overload or short-circuit conditions. Oil-immersed transformers, by contrast, contain mineral oil that can ignite or explode when exposed to an arc or sustained overheating, posing a serious hazard in enclosed or densely populated areas. Installation flexibility is another critical advantage of dry type technology, since these units can be placed indoors near load centers without requiring fire-rated vaults, oil containment pits, or elaborate drainage systems. This proximity to loads reduces the length of low-voltage cables, which in turn lowers resistive losses, improves voltage regulation, and reduces overall installation costs. Furthermore, environmental considerations strongly favor dry type transformers because there are no fluids to leak, no dielectric fluid testing required, and no special disposal procedures needed at the end of the equipment’s useful life.

Maintenance requirements differ substantially between the two technologies, directly affecting total cost of ownership over the transformer’s typical 25- to 30-year service life. Dry type transformers require minimal upkeep, primarily consisting of periodic cleaning of ventilation ducts, inspection of electrical connections for signs of overheating, and verification of the cooling fan operation if forced air is used. Oil-immersed transformers, on the other hand, demand regular oil sampling, dielectric strength testing, dissolved gas analysis, filtration or reclamation of degraded oil, and eventual disposal of contaminated fluid. The reduced maintenance burden of dry type transformers translates into lower operational expenditures and less downtime for facility maintenance teams. Additionally, dry type transformers comply with stringent international standards such as IEC 60076 11, which sets global benchmarks for safety, thermal performance, and dielectric integrity of resin-encapsulated and air-insulated units. Compliance with IEC 60076 11 ensures that medium voltage dry type transformers meet rigorous quality and safety criteria, making them suitable for critical infrastructure projects in hospitals, data centers, and industrial plants.

Guizhou Delong Electric Co., Ltd. offers a comprehensive range of dry type transformers designed to meet diverse operational requirements, voltage classes, and efficiency targets across multiple industries. The cast resin dry type transformer series includes industry-standard models such as SCB10, SCB11, and SCBH15, each engineered for specific performance levels, no-load losses, and load-loss characteristics. These cast resin transformers are manufactured by encapsulating the low-voltage and high-voltage windings in epoxy resin under vacuum conditions, eliminating air voids and providing exceptional mechanical strength as well as resistance to moisture, dust, and chemical contaminants. For applications that demand even higher insulation integrity or operate in particularly harsh environments, Delong also manufactures Vacuum Pressure Impregnated (VPI) transformers that undergo multiple cycles of varnish impregnation and controlled curing. The VPI process ensures that every microscopic void within the winding structure is filled with insulating varnish, maximizing dielectric strength, thermal conductivity, and resistance to partial discharge. Both the cast resin and VPI series are available in various power ratings, primary and secondary voltage combinations, and enclosure configurations to suit specific project specifications, and you can explore the full range on ourProduct page for detailed technical datasheets and model comparisons.

The performance, efficiency, and longevity of a dry type transformer depend heavily on the quality of its core components and the precision with which they are assembled. Guizhou Delong uses low-loss cold-rolled grain-oriented silicon steel laminations in the magnetic core, which significantly reduces eddy current losses and hysteresis losses while keeping the magnetizing current low. The windings are available in either high-purity copper or high-conductivity aluminum, with copper offering superior electrical conductivity and thermal capacity while aluminum provides a cost-effective alternative for projects where budget constraints are a priority. Class F (155 °C) or Class H (180 °C) insulation systems are employed throughout the windings, allowing the transformer to operate at elevated temperatures without degrading the dielectric properties of the insulation. The enclosures are designed and tested to meet various Ingress Protection (IP) ratings, such as IP20 for indoor installations and IP54 for outdoor or dusty environments, protecting internal components from moisture, dust, and physical impact. Tap changers, either off-circuit or on-load, are integrated into the design to allow for fine adjustment of the output voltage, ensuring that the secondary voltage remains within acceptable limits despite fluctuations in the primary supply or load variations.

The core benefits of dry type transformers from Guizhou Delong are numerous and compelling for modern electrical installations where safety, sustainability, and total cost of ownership are top priorities. Enhanced fire safety is achieved through the use of flame-retardant, self-extinguishing materials that do not support combustion, emit toxic smoke, or contribute to the spread of flames in the event of an internal fault. The minimal maintenance requirement of dry type technology translates directly into lower operational costs, fewer scheduled outages, and reduced reliance on specialized service personnel for oil handling and disposal. Environmental friendliness is a key selling point, as dry type transformers contain no oil, PCBs, or other hazardous substances that could contaminate soil, groundwater, or air during operation or at the end of their service life. Flexible installation near load centers improves power quality by shortening cable runs, which reduces voltage drop, capacitive charging currents, and ohmic losses in the distribution system. Finally, the high short-circuit resistance of these transformers, achieved through robust mechanical bracing and vacuum-cast epoxy encapsulation, ensures reliable operation even under severe fault conditions, protecting both the transformer itself and the downstream equipment connected to it.

Dry type transformers from Guizhou Delong are deployed across a broad spectrum of industries and operating environments, each with its own unique set of technical and regulatory demands. Commercial buildings, including office towers, shopping malls, and hotels, benefit from the space-saving, fire-safe design that allows transformers to be installed in electrical rooms within occupied floors rather than in remote, dedicated substations. Hospitals and healthcare facilities rely on dry type units for their ability to operate safely in patient care areas, emergency departments, and operating theaters where the presence of oil-filled equipment would violate fire codes and insurance requirements. Data centers, where uptime is measured in nines and every kilowatt of cooling load matters, use dry type transformers for their high reliability, low maintenance needs, and compatibility with precision air-conditioning systems. Industrial plants and manufacturing facilities utilize medium voltage dry type transformers to power heavy machinery, motor control centers, and process equipment while maintaining a safe working environment. Renewable energy installations, such as solar photovoltaic farms and onshore wind turbines, also employ dry type transformers for step-up applications, benefiting from their compact footprint and resistance to humidity. Underground facilities, tunnels, and subway systems are ideal candidates for dry type technology due to strict ventilation constraints, fire safety regulations, and the need for compact, maintenance-friendly equipment.

Selecting the right dry type transformer requires careful evaluation of several technical parameters to ensure that the unit matches both the present load requirements and any anticipated future expansion of the facility. The power rating, measured in kilovolt-amperes (kVA), must be calculated based on the total connected load, diversity factor, and projected growth, with a safety margin of 10–20 % typically applied to avoid overloading. Voltage requirements, including primary and secondary voltage levels, must align precisely with the utility supply and the voltage rating of the downstream switchgear and equipment. The number of phases (single-phase or three-phase) depends on the nature of the load, with three-phase transformers being the standard choice for commercial and industrial applications. Environmental conditions at the installation site dictate the required IP rating, with indoor installations generally needing IP20 or IP23 and outdoor or washdown areas requiring IP54 or higher. For projects where maximum energy efficiency is a priority, Guizhou Delong offers amorphous alloy core options that reduce no-load losses by up to 70 % compared to conventional silicon steel, significantly lowering the lifetime cost of ownership. Every transformer we manufacture is designed, tested, and certified in accordance with IEC 60076 11 and other relevant international standards, guaranteeing compliance with local regulations and global best practices. If you have specific requirements that fall outside our standard product range, we encourage you to contact ourCustomized service team, who can develop a tailored solution that fits your exact voltage, rating, and mechanical specifications.

Choosing the right transformer is a strategic decision that impacts the safety, efficiency, and operational costs of your electrical distribution system for decades to come, and dry type technology offers a clear path to achieving all three objectives simultaneously. Guizhou Delong Electric Co., Ltd. stands ready to deliver customized dry transformer solutions that meet your exact technical specifications, project timeline, and budget constraints, backed by decades of engineering experience and a commitment to quality. Our team of experienced engineers can guide you through every stage of the selection process, from initial load analysis and system modeling to factory acceptance testing and site commissioning. We pride ourselves on manufacturing transformers that combine cutting-edge electromagnetic design, premium materials, and rigorous quality control to deliver reliable performance under the most demanding conditions. By partnering with Guizhou Delong, you gain access to high-quality products, responsive technical support, and comprehensive after-sales service that protects your investment over the entire equipment lifecycle. Stay updated with our latest product innovations, industry news, and case studies by visiting ourNews page, and do not hesitate to contact us directly for a consultation or quotation. For a deeper look into our company’s history, certifications, and manufacturing philosophy, please visit our About Us page, where you will find detailed information about what makes Delong the preferred partner for dry type transformer solutions worldwide.