Smart Power, Superior Savings. Our Unit Substation Transformers.
01 General
1.1 Project Description
750/862 kVA unit substation transformer was delivered to Canada in 2025. The rated power of the transformer is 750/862 kVA with KNAN/KNAF cooling. The primary voltage is 13.8 kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.48/0.277 kV, they formed a vector group of Dyn1.
Engineered for superior performance and reliability, this 750/862 kVA unit substation transformer delivers a complete power solution tailored for demanding commercial and industrial applications. It features FR3® natural ester fluid for enhanced fire safety and extended insulation life, coupled with optimized thermal performance (Top Oil: 45K, Winding Avg: 50K, Hot Spot: 63K) to ensure efficiency and durability under peak load conditions. The transformer is resistance-grounded for improved system protection and comes fully equipped with integrated accessories-including a CT cabinet for metering and protection, detachable radiators with fan cooling, wheels for easy positioning, a rapid pressure rise relay for internal fault prevention, and lightning arresters for surge protection-providing a ready-to-install, comprehensive power package designed for safety, reliability, and ease of maintenance.
1.2 Technical Specification
750/862 kVA unit substation specifications type and data sheet
| Delivered to | America |
| Year | 2025 |
| Type | Substation transformer |
| Standard | ANSI C57.12.00 |
| Rated Power | 750/862 kVA |
| Frequency | 60HZ |
| Phase | 3 |
| Cooling Type | KNAN/KNAF |
| Primary Voltage | 13.8 kV |
| Secondary Voltage | 0.48/0.277 kV |
| Winding Material | Copper |
| Angular displacement | Dyn1 |
| Impedance | 6% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | ≤1.16kW |
| On Load Loss | ≤7.08kW |
1.3 Drawings
750/862 kVA unit substation diagram drawing and size.
02 Manufacturing
2.1 Core
The core is precision-built with high-grade, cold-rolled grain-oriented silicon steel. This material, along with the advanced laminated design, minimizes magnetic losses and energization current. Its robust construction ensures low noise levels and mechanical strength, providing a stable and efficient magnetic path that is fundamental to the transformer’s reliability and performance.
2.2 Winding
 | The windings are optimally constructed for performance and reliability. The low-voltage winding utilizes a foil-wound design, providing excellent mechanical strength, superior heat dissipation, and high short-circuit withstand capability. Complementing it, the high-voltage winding employs a precision layer-wound technique with robust inter-turn insulation, ensuring precise voltage transformation and enhanced dielectric strength. This proven combination delivers exceptional efficiency, stability, and durability. |
2.3 Tank
| The tank is a robust, welded steel structure designed for durability and performance. It serves as a protective enclosure for the core and windings, provides a sealed reservoir for insulating liquid, and features radiators for efficient heat dissipation. Engineered to withstand environmental and operational stresses, the tank ensures the transformer’s long-term integrity and reliability. |  |
2.4 Final Assembly
 | The final assembly is the precision integration of the core, windings, tank, and accessories into a unified and robust system. This critical phase ensures all internal electrical connections are secured, mechanical structures are sound, and the enclosure is perfectly sealed. The outcome is a fully self-contained, ready-for-operation power unit that delivers designed performance, durability, and reliability. |
03 Testing
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | Maximum resistance unbalance rate | 3.19 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% | -0.05~0.01 | Pass |
| 3 | Phase-relation tests | / | Dyn1 | Dyn1 | Pass |
| 4 | No-load losses and excitation current | % | I0 :: provide measured value | 0.47 | Pass |
| kW | P0: provide measured value | 0.938 | |||
| / | the tolerance for no load loss is +0% | / | |||
| 5 | Load losses , impedance voltage, total losses and efficiency | / | t:85℃ the tolerance for impedance is +7.5% the tolerance for total load loss is +0% | / | Pass |
| % | Z%: measured value | 6.20 | |||
| kW | Pk: measured value | 6.903 | |||
| kW | Pt: measured value | 7.841 | |||
| % | Efficiency not less than 99.16% | 99.21 | |||
| 6 | Applied Voltage Test | / | HV:34kV 60s LV: 10kV 60s | No collapse of the test voltage occurs | Pass |
| 7 | Induced Voltage Withstand Test | / | Applied voltage (KV):0.96 | No collapse of the test voltage occurs | Pass |
| Duration(s):40 | |||||
| Frequency (HZ): 180 | |||||
| 8 | Insulation Resistance Measurement | GΩ | HV-LV to Ground: | 8.18 | Pass |
| LV-HV to Ground: | 3.79 | ||||
| HV&LV to Ground: | 8.98 | ||||
| 9 | Leakage Test | / | Applied pressure：50kPA | No leakage and no Damage | Pass |
| Duration：12h | |||||
| 10 | Lightning impulse test | kV | full wave | No collapse of the test voltage occurs | Pass |
| 11 | Oil Test | kV | Dielectric Strength Measured value ≥ 45 kV | 68.4 | Pass |
| mg/kg | Moisture Content | 168.6 | |||
| % | Dissipation Factor | 3.751 | |||
| mg/kg | Furan Analysis | / | |||
| / | Gas Chromatography Analysis | / |
04 Packing and Shipping
4.1 Packing
The unit substation is packaged with a focus on secure protection and handling efficiency. It is typically crated on a robust, skidded base for structural integrity and forklift access. Critical components are braced, and the entire unit is weather-proofed to ensure safe transit and storage, arriving on-site ready for installation.
4.2 Shipping
The unit substation is prepared for ocean freight to the United States with robust, weather-sealed crating secured to an international shipping container. It is clearly marked with lifting points, center-of-gravity indicators, and customs documentation to ensure safe handling, stable transit, and efficient clearance upon arrival at the U.S. port.
05 Site And Summary
More than just a component, this Unit Substation Transformer is the reliable heart of your electrical infrastructure. It embodies a commitment to durability, safety, and efficiency, engineered to deliver uninterrupted power for your most critical operations. Choose it as the cornerstone of your project for performance that endures.
Contact us today to engineer a solution tailored to your specific needs.
