Usune Electric’s 13.8kV 250kVA dry type distribution transformer is an oil-free power distribution unit. Its windings feature a vacuum-cast epoxy resin structure, relying on air for insulation and heat dissipation, thereby completely eliminating safety hazards associated with oil-immersed transformers—such as oil leaks, fires, and explosions.
As a reliable global supplier for indoor power distribution projects, Usune has optimized the core and winding structures to achieve low losses, low noise, and low partial discharge. The unit is designed to withstand high humidity, dust, and enclosed underground operating environments. It requires no oil containment pits or fire-rated isolation rooms, offering a safe, eco-friendly solution for stable, long-term voltage transformation. With a capacity range of 30–2500kVA, the product is compatible with power supply systems for global commercial, medical, rail transit, and industrial facilities.
The 13.8kV 250kVA dry type distribution transformer is suitable for commercial complexes, office buildings, hospitals, educational institutions, manufacturing plants, subway substations, and any indoor power distribution location requiring high fire safety standards.
The windings utilize high-temperature resistant insulation materials, and the unit contains no insulating oil. It will not catch fire, explode, or leak liquid during overload faults, eliminating the need for additional fire-rated isolation rooms.
There is no risk of oil contamination, and no harmful gases are released during normal operation or fault conditions. It can be installed directly indoors without oil treatment facilities, meeting environmental standards for green buildings and medical facilities.
Optimized core and winding structures result in low operational vibration and noise. Excellent control of partial discharge levels slows insulation aging and extends the unit's overall service life.
The iron core utilizes high-grade silicon steel sheets, resulting in lower no-load and load losses; long-term operation significantly reduces electricity costs for buildings and factories.
Featuring an air-insulated, air-cooled structure, it eliminates the need for periodic insulation oil replacement or testing; only simple routine dusting is required, drastically cutting labor and material costs for operation and maintenance.
Suitable for ambient temperatures of -20°C to +40°C, altitudes ≤1000m, and relative humidity ≤95% (non-condensing). Moisture- and dust-resistant, making it ideal for underground spaces and humid coastal factory environments.
Smaller volume and lighter weight for the same capacity; occupies minimal space in the power distribution room, facilitates transport and hoisting, and reduces the scope of on-site civil engineering work.
The Usune 13.8kV 250kVA dry type distribution transformer operates based on the principle of electromagnetic induction:
1.Alternating current (AC) is fed into the high-voltage primary winding, generating alternating magnetic flux within the
iron core;
2. The alternating magnetic flux passes through the secondary winding, inducing electromotive force in the low-voltage
coil via electromagnetic induction;
3. Voltage transformation between 13.8kV and 0.4kV is achieved based on the turns ratio between the primary and
secondary windings, enabling power transmission.
Key difference from oil-immersed transformers: Air serves as the sole medium for insulation and heat dissipation between the windings and the iron core; there is no liquid insulating oil. It relies on natural air cooling for heat dissipation (with forced-air fans available for heavy-load conditions), ensuring safe and stable power conversion.
| Item | Standard Technical Parameter |
| Rated Capacity Range | 30～2500 kVA (customized 250kVA model for this product) |
| High Voltage Rated | 10kV / 10.5kV / 13.8kV |
| Low Voltage Rated | 0.4kV |
| Rated Frequency | 50Hz / 60Hz dual optional for global markets |
| Vector Group | Dyn11 |
| Impedance Voltage | 4%~6%, standard configuration 6% |
| Item | Standard Technical Parameter |
| Operating Ambient Temperature | -20℃ ~ +40℃ |
| Max Applicable Altitude | ≤1000m |
| Allowable Relative Humidity | ≤95%, no condensation on surface |
| Mandatory Installation Condition | Indoor environment |
The underground distribution room was enclosed and humid with strict fire safety requirements; the project selected the Usune 250kVA dry-type transformer. It has operated continuously for three years with no oil leaks or partial discharge alarms, eliminating the risk of underground fires associated with oil-filled transformers and reducing routine maintenance workload by 90%.
The equipment powers operating rooms, ICUs, and medical imaging systems. Its oil-free design eliminates fire hazards in medical areas; low-noise operation ensures patient comfort, while the maintenance-free design reduces the workload for the hospital's electrical maintenance staff.
The workshop operates at full load 24 hours a day in a high-dust environment, utilizing multiple Usune 250kVA transformers to support automated production lines. Low-loss cores reduce electricity costs, the compact footprint saves space in the power distribution room, and dust-proof insulation ensures stable power supply for precision equipment.
A: Standard models are designed for indoor installation only. However, if outdoor installation is required, Usune offers customized solutions with IP54-rated outdoor enclosures to ensure safe outdoor operation.
A: Usune windings feature vacuum-cast epoxy resin, providing solid insulation. This results in partial discharge metrics far superior to those of open-winding dry-type transformers, as well as enhanced moisture and dust resistance, making them ideal for harsh environments such as underground facilities, hospitals, and high-humidity areas.
A: Yes. Usune supports customized off-circuit tap changers on the high-voltage side to accommodate voltage fluctuations in various national grids; the units are compatible with both 50Hz and 60Hz frequencies and meet power supply standards across Asia, the Americas, and Europe.
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