The Evenson Power Dry Type Transformer uses air and solid insulation instead of oil, making it the safe, low-maintenance choice for indoor, populated, and fire-sensitive environments.
Dry type transformers eliminate insulating oil entirely, relying instead on air for cooling and solid, high-temperature insulation systems for dielectric strength. This makes them inherently fire-safe, environmentally clean, and ideally suited to locations where an oil-filled unit would be impractical or hazardous, such as inside buildings, basements, hospitals, data centers, ships, and underground installations.
The Evenson Power Dry Type range combines proven magnetic and insulation engineering with rugged construction to provide reliable, maintenance-light power distribution wherever safety and indoor placement are priorities.
A dry type transformer transfers energy between windings using a magnetic core and solid insulation, cooled by the natural or forced circulation of air rather than liquid. Because there is no flammable fluid, these units carry a low fire risk, require no oil containment, and can be located directly at the load center.
Evenson Power offers dry type transformers from 300 kVA up to large units, with medium-voltage classes typically at 35 kV and below for distribution duty. Several insulation technologies are available to match the environment, from economical open-wound units for clean indoor spaces to fully encapsulated cast-resin units for harsh, humid, or polluted conditions.
Evenson Power dry type transformers are built around a low-loss magnetic core of grain-oriented silicon steel (CRGO) or, for the lowest no-load losses, amorphous metal. Windings are copper or aluminum, and the insulation system is selected from several proven technologies.
Open-wound designs use a dip-and-bake process with varnish coating for clean, dry indoor environments. Vacuum Pressure Impregnated (VPI) windings are sealed under vacuum with high-temperature polyester resin for improved moisture and contamination resistance. Vacuum Pressure Encapsulated (VPE) units add a thicker silicone-resin coating for tougher conditions. Cast Coil (cast resin) windings are solidly cast in epoxy resin under vacuum in a mold, producing a robust, moisture-proof, mechanically strong coil ideal for the most demanding and humid environments.
Insulation systems are rated to recognized thermal classes, typically Class F (up to 155 degrees C) and Class H (up to 180 degrees C), giving strong overload tolerance and long insulation life. Leakage reactance is controlled in design, often kept low for good voltage regulation.
The Evenson Power Dry Type range spans 300 kVA upward, covering commercial step-down duty through substantial industrial loads. Distribution dry type units serve medium-voltage classes of 35 kV and below, with low-voltage secondaries selected to the application.
Standard 50 Hz and 60 Hz options are available, with impedance and tap arrangements specified to suit the installation. Low-impedance designs are emphasized where tight voltage stability is required.
The absence of oil removes fire and environmental hazards, eliminates the need for oil testing and containment, and allows installation directly inside occupied buildings. Solid insulation systems give excellent short-circuit strength and overload capability.
High efficiency, with well-designed units reaching well into the upper-90s percent, reduces running cost, and the rugged construction supports a long service life with minimal intervention. Cast-resin and encapsulated designs are highly resistant to humidity, dust, and aggressive atmospheres.
Dry type transformers are the standard choice for commercial buildings, hospitals, schools, shopping centers, airports, and data centers, where fire safety and indoor placement are essential. They serve industrial plants, marine and offshore installations, mining, and underground or tunnel power systems.
They are equally at home in renewable-energy collection, traction and rail power, and any application demanding clean, maintenance-light operation close to the load.
Evenson Power dry type transformers are designed and tested to recognized international standards for dry type and cast-resin transformers, covering thermal class, losses, dielectric performance, and where applicable partial-discharge and climatic/fire-behavior classifications.
Routine factory tests include turns ratio, winding resistance, no-load and load losses, impedance, and applied- and induced-voltage dielectric tests. Partial-discharge measurement is standard on cast-resin units. Supported compliance marks include IEC, UL, CE, KEMA, and TUV.
Dry type units install directly at the load center, often in an indoor enclosure, with simple busbar or cable connections and no oil-handling infrastructure. Adequate ventilation must be provided so the air-cooling system can dissipate heat; forced-air (fan) cooling can boost rating where space is limited.
Maintenance is minimal: periodic de-energized cleaning to remove dust from windings and cooling passages, visual inspection of connections and insulation, and verification of any temperature monitoring. With no oil, there is no fluid sampling, no leaks, and no containment to manage.
Evenson Power Dry Type Transformers pair safety with performance: oil-free operation that protects people and property, combined with low-loss cores and high-grade insulation that deliver efficiency and long life. The full range of insulation technologies lets customers match the exact unit to their environment.
With strict quality control, partial-discharge-verified cast-resin coils, and responsive engineering support, Evenson Power dry type transformers are a dependable foundation for modern indoor power distribution.
Evenson Power dry-type transformers eliminate the use of insulating oil, removing the associated fire load, spill risk, and containment requirements. Cast-resin and VPI insulation systems are self-extinguishing and classified to demanding fire-behaviour categories, making these units the preferred choice for hospitals, high-rise buildings, data centres, tunnels, marine installations, and other locations where occupant safety and asset protection are paramount.
Because there is no oil to leak or degrade, dry-type units can be installed close to the load with minimal environmental safeguards, reducing cable runs and losses. The insulation system is resistant to moisture, dust, and industrial pollutants, and units intended for harsh environments can be supplied with increased climatic and environmental class ratings to withstand condensation and aggressive atmospheres.
Low partial discharge design and the absence of combustible fluid also reduce the risk of toxic smoke during a fault, supporting compliance with strict building and life-safety codes.
The solid insulation system of an Evenson Power dry-type transformer makes maintenance simple and infrequent. With no oil to sample, filter, or replace, routine service is largely limited to periodic cleaning of the windings and ventilation paths and inspection of connections for tightness and discoloration. This makes dry-type units especially well suited to installations where access for heavy maintenance is difficult or where downtime is costly.
Cast-resin windings are robust against mechanical shock, vibration, and short-circuit forces, and the encapsulation protects the conductor from environmental attack throughout a long service life. Optional forced-air cooling can be added to provide additional capacity during peak loading without compromising insulation longevity, and temperature monitoring with PT100 sensors and a digital controller allows operators to track winding temperatures continuously.
With proper cleaning and a clean, ventilated installation, these transformers reliably deliver decades of service with minimal lifecycle cost.
| Type | Dry type (air-cooled) transformer |
| Power Rating | From 300 kVA upward |
| Medium-Voltage Class | 35 kV and below (distribution) |
| Low-Voltage Secondary | Application-specific (e.g. 400/415 V, 480 V) |
| Frequency | 50 Hz / 60 Hz |
| Insulation Technology | Open-wound / VPI / VPE / Cast resin |
| Thermal Class | Class F (155 C) / Class H (180 C) |
| Cooling | AN (air natural) / AF (air forced) |
| Core Material | CRGO silicon steel or amorphous metal |
| Winding Material | Copper or aluminum |
| Tap Changer | Off-circuit, typ. +/-2 x 2.5% |
| Partial Discharge | Verified on cast-resin units |
| Enclosure | Open core/coil or IP-rated metal enclosure |
| Fire Behavior | Self-extinguishing, low fire load |
| Standards | IEC / UL / CE / KEMA / TUV |
| Typical Applications | Indoor commercial, industrial, marine, infrastructure |
Engineered, certified and delivered under the Evenson Power name.
