Smart Power Distribution, Green Future – Opening Winding Dry Transformers for Sustainability!
01 General
1.1 Project Description
The 630 kVA opening winding dry type transformer was delivered to South Africa in 2025. The rated power of the opening winding dry 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.
Our vacuum pressure impregnated transformer is engineered for superior performance, combining advanced technology with robust construction to meet demanding industrial and commercial power needs. Featuring an intelligent temperature controller, it ensures optimal thermal management, while built-in cooling fans enhance heat dissipation for consistent efficiency even under heavy loads.
Designed with Class H insulation, this vacuum pressure impregnated transformer withstands high-temperature environments, supporting a 100K temperature rise for reliable long-term operation. Compatible with 110V power supply, it delivers stable voltage transformation with minimal energy loss.
Ideal for industrial automation, renewable energy systems, and critical infrastructure, our dry-type transformer offers maintenance-free operation, enhanced safety (no fire risk), and eco-friendly performance (no oil or toxic emissions). Upgrade to a smarter, more resilient power solution today!
1.2 Technical Specification
630 kVA vacuum pressure impregnated transformer specification and data sheet
| Delivered to | South Africa |
| 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 vacuum pressure impregnated transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The vacuum pressure impregnated transformer features a high-permeability silicon steel laminated core that undergoes precision annealing treatment to minimize magnetic circuit losses. The core adopts a stepped stacking structure to effectively reduce eddy current losses, combined with special clamping technology to ensure quiet, noise-free operation. |  |
2.2 Winding
 | The transformer features precision-wound aluminum wires with multi-layer SHS (Super Heat-resistant Synthetic) insulation, capable of withstanding temperatures up to 220°C. Its innovative open-ventilation design ensures optimal heat dissipation while maintaining Class H thermal performance (100K temperature rise). The winding structure combines reinforced mechanical stability with excellent dielectric strength, offering superior resistance to thermal shock, vibration and partial discharge. |
2.3 Final Assembly
| 1) Precision mounting of SHS-insulated coils onto CRGO cores; 2) Stepped-lamination upper yoke installation with 15-20kN/m clamping force; 3) install cooling fans and PT100 smart temperature controller (150℃ alarm/180℃ trip); 4) install terminal connections passing 5000V insulation tests (>1000MΩ). |  |
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 |
| 0.29% | 0.84% | |||||
| 2 | Measurement of voltage ratio and check of phase displacement | / | The tolerance of voltage ratio on the principal tapping: ±1/10 Connection symbol: Dyn11 | -0.02% ~ 0.13% Dyn11 | Pass | |
| 3 | Measurement of Short-circuit Impedance and Load Loss | / kW kW | t:145℃ Z%: measured value Pk: measured value Pt: measured value | 6.22% 4.745 6.485 | 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 | 0.36 0.978 | Pass |
| 100% Ur | 0.40 1.087 | |||||
| 110% Ur | 0.44 1.195 | |||||
| 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 vacuum pressure impregnated transformer is packed in sturdy wooden crates with inner cushioning for safe transportation. All components, including the temperature controller and fans, come pre-installed as a complete unit. The exterior is clearly marked with handling instructions, providing reliable moisture and shock protection for long-distance transformer shipping. |  |
4.2 Shipping
 | The vacuum pressure impregnated transformer will be shipped CIF Durban Port in shock-proof wooden crates. The price covers marine insurance and export customs clearance, while import formalities shall be handled by the receiver. The shipment maintains strict humidity/ temperature control in compliance with international anti-corrosion standards for sea freight. |
05 Site And Summary
As a high-efficiency solution for power transmission and distribution, our Dry Type Transformer delivers enduring reliability to industrial, energy, and infrastructure sectors through innovative open-design, superior thermal management, and robust insulation. Combining maintenance-free operation, eco-friendly construction, and intelligent temperature control, it excels in demanding applications while supporting sustainable energy goals. Partner with us for trusted power solutions-where technology meets safety and efficiency, empowering smarter energy delivery.
