Safety Meets Sustainability: Choose VPI Dry Type Transformers for a Greener, Oil-Free Solution!
01 General
1.1 Project Description
The 630 kVA vpi type transformer was delivered to South Africa in 2025. The rated power of the vpi type transformer is 630 kVA with AN/AF cooling, the primary voltage is 11 kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.55kV, they formed a vector group of Dyn11.
VPI (Vacuum Pressure Impregnated) dry type transformers are engineered with a strong emphasis on environmental sustainability and economic efficiency. Designed to significantly reduce fire risks due to their low combustibility, these transformers minimize the potential for environmental pollution while ensuring stable operation even in challenging atmospheric conditions. Utilizing advanced NOMEX insulation material, our VPI transformers deliver superior dielectric properties and enhanced heat resistance between the electrical windings, leading to improved safety and resilience against flooding.
Whether deployed in educational institutions, healthcare facilities, industrial sites, or commercial structures, the dry type transformer ensures reliable stability and cost-effective power solutions. With exceptional design and material quality, these transformers are ideally suited for any application that demands safety and performance.
1.2 Technical Specification
630 kVA vpi type transformer specification and data sheet
| Delivered to | Jamaica |
| Year | 2025 |
| Type | Open winding dry type transformer |
| Core material | Grain oriented silicon steel sheet |
| Standard | IEC60076 |
| Rated Power | 630kVA |
| Frequency | 50HZ |
| Vector group | Dyn11 |
| Phase | 3 |
| Cooling Type | ONAN/ONAF |
| Primary Voltage | 11 kV |
| Secondary Voltage | 0.55 kV |
| Winding Material | Aluminum |
| Impedance | 6% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5%@primary side by tapping links |
| No Load Loss | 1.1KW |
| On Load Loss | 8.3KW |
| Insulation level | H |
1.3 Drawings
630 kVA vpi type transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The core of the VPI (Vacuum Pressure Impregnated) dry-type transformer is made from high-quality, non-aging silicon steel, designed for optimal magnetic permeability. Featuring cold-rolled, oriented laminations, it minimizes energy losses and operates efficiently below saturation levels. The precision-engineered laminations eliminate gaps, ensuring a tight fit for enhanced performance. A robust clamping framework provides stability and support for the coil assembly. Construction options include standard butt-lap or mitered configurations. Vibration-dampening pads isolate the core from external disturbances, while a protective coating ensures durability and reliability in various operating conditions. |  |
2.2 Winding
 | The coils of the vpi type transformer are designed for optimal performance and reliability. The low-voltage coil is wound using foil winding technology, which enhances the efficiency of the coil and minimizes energy losses. This coil is insulated with SHS (Silicon High Strength) material, providing excellent electrical insulation and mechanical strength. The high-voltage coil, on the other hand, is constructed using wire winding methods. Each high-voltage winding is carefully wrapped with insulating material to ensure safe and effective operation. Furthermore, the entire assembly undergoes vacuum pressure impregnation (VPI) to enhance insulation and protect against environmental factors, ensuring longevity and stability under varying operational conditions. |
2.3 Final Assembly
| 1. Coil Fixing: Securely install the pre-cast coils onto the core according to design requirements, ensuring that the direction, connection methods, and spacing of the coils comply with design specifications to guarantee normal electrical performance. 2. Electrical Connections: Connect the high-voltage and low-voltage cables, ensuring all connections are secure and meet standards. 3. Upper and Lower Clamping Yoke Assembly: Accurately align and securely fasten the upper and lower clamping components to the yoke to ensure structural stability and overall strength of the transformer. 4. Accessory Installation: Install various accessories such as temperature controllers, fans to ensure the proper functioning of auxiliary equipment. |  |
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 |
| 0.21% | 0.11% | |||||
| 2 | Measurement of voltage ratio and check of phase displacement | / | The tolerance of voltage ratio on the principal tapping: ±1/10 Connection symbol: Dyn11 | -0.03% ~ 0.10% Dyn11 | Pass | |
| 3 | Measurement of Short-circuit Impedance and Load Loss | / kW kW | t:120℃ Z%: measured value Pk: measured value Pt: measured value | 6.16% 4.529 6.048 | 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 | 0.468 1.006 | Pass |
| 100% Ur | 0.52 1.118 | |||||
| 110% Ur | 0.572 1.229 | |||||
| 5 | Applied Voltage Test | / | HV: 35kV 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): 1.1 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
| The vpi type transformer is packed in a fully enclosed moisture-proof wooden crate with anti-corrosion aluminum foil wrapping. Customized shock-absorbing brackets and cushioning materials are applied to protect critical components. The packaging meets IEC 60076-11 standards, suitable for ocean shipping and harsh environment transportation. |  |
4.2 Shipping
 | The vpi type transformer was transported under CIF (Cost, Insurance, and Freight) conditions to Durban. It will be securely packed with protective materials to prevent damage, loaded onto the shipping vessel, and insured during transit. Upon arrival, the transformer will undergo customs clearance in accordance with local regulations, after which it will be carefully unloaded and transported to the final delivery location for installation. All necessary precautions will be taken to ensure safe and timely delivery. |
05 Site And Summary
In conclusion, the vpi type transformer represents a pinnacle of modern transformer technology, combining durability, safety, and environmental sustainability. Its advanced design and high-quality materials ensure reliable performance across diverse applications, from industrial facilities to commercial buildings. With low combustibility and excellent resistance to electrical disturbances, the VPI transformer not only meets but exceeds industry standards. Choosing a VPI dry type transformer means investing in a future where efficiency and safety go hand in hand, ultimately contributing to a more sustainable energy landscape.
