Eco-Friendly Power Solutions – Zero Oil, Zero Toxins, 100% Efficiency!
01 General
1.1 Project Description
400 kVA dry type transformer was delivered to Salvador in 2025. The rated power of the transformer is 400 kVA with ONAN cooling. The primary voltage is 0.55 kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.4 kV, they formed a vector group of Dyn11.
The Dry Type Transformer combines cutting-edge technology with robust design to deliver superior performance, safety, and efficiency. Encased in a durable, protective enclosure, this transformer is ideal for demanding environments, offering enhanced resistance to moisture, dust, and corrosion.
Equipped with an advanced temperature controller, it ensures optimal thermal management, preventing overheating and extending operational life. For additional cooling under high loads, integrated fans provide efficient airflow, maintaining stable performance even in challenging conditions.
Designed for maintenance-free operation, this flame-resistant, oil-free transformer is perfect for industrial plants, commercial buildings, and renewable energy applications-where reliability, safety, and sustainability matter most. Trust in innovation. Power with confidence.
1.2 Technical Specification
400 kVA dry type transformer specification and data sheet
| Delivered to | Salvador |
| Year | 2025 |
| Type | dry type transformer |
| Core material | Grain oriented silicon steel sheet |
| Standard | IEC60076 |
| Rated Power | 400kVA |
| Frequency | 60HZ |
| Vector group | Dyn11 |
| Phase | 3 |
| Cooling Type | ONAN/ONAF |
| Primary Voltage | 0.55 kV |
| Secondary Voltage | 0.46 kV |
| Winding Material | Copper |
| Impedance | 2~5% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5%@primary side |
| No Load Loss | 1.05KW |
| On Load Loss | 4.3KW |
1.3 Drawings
400 kVA dry type transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| • Premium Grain-Oriented Silicon Steel – Reduces hysteresis and eddy current losses, ensuring superior magnetic performance and lower no-load current. • Precision Stacking (Laminated Core) – Thin, insulated steel layers are tightly stacked to minimize core losses while enhancing mechanical stability. • Optimized Magnetic Path – Advanced core geometry improves flux distribution, boosting efficiency and thermal performance. |  |
2.2 Winding
 | The dry type transformer utilizes pre-impregnated (pre-preg) insulation cloth in its coil construction to ensure superior dielectric strength and thermal stability. The pre-preg process saturates the insulating fabric with high-grade resin before winding, allowing for precise, void-free encapsulation when cured. This results in a completely solid, moisture-proof transformer winding system with excellent mechanical rigidity and resistance to thermal cycling. |
2.3 Final Assembly
| 1. Winding Installation: Mount the pre-impregnated fabric-type windings onto the core limbs, ensuring proper alignment and secure fastening. 2. Core Lamination: Insert the remaining silicon steel laminations at the top of the core to complete the magnetic circuit, then clamp and secure the core. 3. Bushing Installation: Install HV/LV bushings, connect winding leads, and ensure electrical insulation and mechanical strength. 4. Accessory Assembly: Mount cooling fans, wire them, and test rotation direction. Install temperature controllers (PT100), placing sensors at winding hotspots. 5. Enclosure Placement: Hoist the transformer into the metal enclosure and secure the base. |  |
03 Testing
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion | |
| 1 | Measurement of winding resistance | / | Maximum resistance unbalance rate Line resistance:≤2% | HV (line) | LV (line) | Pass |
| 0.49% | 0.62% | |||||
| 2 | Measurement of voltage ratio and check of phase displacement | / | The tolerance of voltage ratio on the principal tapping: ±1/10 Connection symbol: Dyn11 | 0.49% ~ 0.15% Dyn11 | Pass | |
| 3 | Measurement of Short-circuit Impedance and Load Loss | / kW kW | t:145℃ Z%: measured value Pk: measured value Pt: measured value | 4.16% 4.630 5.597 | Pass | |
| 4 | Measurement of No-load Loss and Current at 90% and 110% of rated voltage | / kW | I0 :: provide measured value P0: provide measured value | 90% Ur | 0.63 0.870 | Pass |
| 100% Ur | 0.70 0.967 | |||||
| 110% Ur | 0.77 1.063 | |||||
| 5 | Applied Voltage Test | / | HV: 3kV 60s LV: 3kV 60s | No collapse of the test voltage occurs | Pass | |
| 6 | Induced Voltage Withstand Test | / | Applied voltage (KV): 2 Ur Induced voltage (KV): 0.92 Duration(s):40 Frequency (HZ): 150 | No collapse of the test voltage occurs | Pass | |
| 7 | Partial Discharge Test | pC | The maximum level of partial discharges shall be 10 pC | ＜10 | Pass | |
04 Packing and Shipping
4.1 Packing
| This product adopts industrial-grade protective packaging to ensure transportation safety: The transformer body is wrapped in dust-proof plastic film and secured in a wooden frame crate (40mm waterproof plywood), with EPE pearl cotton cushioning (≥50mm) and desiccant packets placed inside. Protective angles are installed on the edges of the transformer enclosure, while the base is stabilized with wooden blocks and secured by four-point nylon straps. The packaging is clearly marked with lifting symbols, center of gravity indicators, and waterproof/shockproof warnings. The package includes a laminated certificate of compliance, a bilingual (Chinese-English) manual, and a packing list. Standard packaging meets ISTA 3A transportation testing requirements, with optional customized solutions such as container-adapted or vacuum-sealed moisture-proof packaging. |  |
4.2 Shipping
 | This resin cast dry-type transformer will be shipped to ACAJUTLA Port, El Salvador under CIF terms. Packed in IPPC-certified moisture-proof wooden crates (40mm waterproof plywood + EPE cushioning) and loaded in 20’/40′ container shipping. Includes marine insurance from Shanghai ports, with original B/L, commercial invoice, bilingual packing list, and CHINA-CAFTA Certificate of Origin. Vibration monitors installed during transit, with Spanish/English “Top Load Only” labels. Complies with Salvadoran NSO 59.37.01 standards. |
05 Site And Summary
As a new-generation eco-friendly power solution, this resin cast dry-type transformer stands out with its exceptional fire safety, maintenance-free design and extended service life, making it the ideal choice for industrial, commercial and renewable energy applications. The fully sealed construction with intelligent temperature control ensures reliable performance even in harsh environments. Every unit is rigorously tested to meet international safety standards, backed by our professional technical support. Choose our product for a safer, more efficient and sustainable energy future.
