2250 kVA pad mounted transformer-engineered for solar farms, built for safety, efficiency, and a greener energy future
01 General
1.1 Project Description
To support the expanding deployment of solar energy systems in the U.S. market, we delivered a 2250 kVA three-phase pad-mounted transformer specifically tailored for utility-scale photovoltaic (PV) applications. Designed with a robust five-leg core structure and dead-front, loop-feed configuration, this unit ensures safety, reliability, and system flexibility in renewable energy environments.
This 2250 kva pad mounted transformer operates with a primary voltage of 12.47 GrdY/7.2 kV and a secondary voltage of 0.6Y/0.347 kV, making it ideal for interfacing with solar inverters and downstream distribution networks. The vector group YNyn0 enables effective grounding and facilitates low-voltage three-phase load connections in solar farms. With aluminum windings, the unit offers a balance between performance and cost efficiency.
Built with FR3 natural ester fluid, the transformer achieves a high level of environmental sustainability and fire safety, thanks to its high flash point (>300°C) and biodegradability. The KNAN (natural air-cooled) design reduces operational complexity and maintenance needs while ensuring excellent thermal performance.
Delivered on schedule, this transformer contributes directly to the client’s solar infrastructure expansion, supporting the broader national goals of decarbonization and grid modernization. It demonstrates our capability to engineer high-performance, utility-grade equipment for the evolving needs of the renewable energy sector.
1.2 Technical Specification
2250 kva pad mounted transformer specification and data sheet
| Delivered to | America |
| Year | 2025 |
| Type | Three phase pad mount transformer |
| Standard | IEEE Std C57.12.34-2022 |
| Rated Power | 2250KVA |
| Frequency | 60HZ |
| Feed | Loop |
| Front | Dead |
| Phase | three |
| Cooling Type | KNAN |
| Liquid insulant | FR3 Oil |
| Primary Voltage | 12.47 Kv |
| Secondary Voltage | 0.6 Kv |
| Vector Group | YNyn0 |
| Winding Material | Aluminum |
| Impedance | 5.75% |
| Efficiency | 99.52% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 2.4 KW |
| On Load Loss | 15.79KW |
| Accessories | Standard Configuration |
1.3 Drawings
2250 kva pad mounted transformer dimensions and weight details
02 Manufacturing
2.1 Core
The five-leg core design ensures superior handling of zero-sequence flux and unbalanced loading conditions, which are common in distributed energy systems. Its loop-feed and dead-front construction aligns with U.S. safety standards and enables convenient installation in solar fields, substations, and public-access areas.
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2.2 Winding
 | This 2250 kva pad mounted transformer features a high-voltage winding with a wire-wound design, providing a high number of turns to ensure uniform voltage distribution and excellent insulation performance. The low-voltage winding uses a foil construction to handle higher currents efficiently while minimizing losses. The YNyn0 vector group configuration supports grounded neutrals on both high and low voltage sides, enhancing system safety and stability-key requirements for photovoltaic applications. Additionally, the dual low-voltage ratings allow flexible connections to various load configurations, improving overall system reliability and adaptability in solar power projects. |
2.3 Tank
The 2250 kva pad mounted transformer includes a sealed oil tank made of mild steel, coated with a robust white powder finish (RAL 9003) to enhance corrosion resistance. A bolted cover ensures a secure seal, protecting the insulating oil inside. The transformer features corrugated radiators integrated on both sides and the rear of the oil tank, which serve as passive cooling elements by increasing the external surface area for natural air convection. These radiators are securely welded and seal-connected to the main tank body to ensure leak-free operation under thermal cycling. Precision welding at the interface ensures mechanical strength and oil-tight integrity, while also allowing for thermal expansion without compromising structural stability or cooling performance. |  |
2.4 Final assembly
 | In the final assembly stage, this 2250 kVA pad-mounted transformer designed for solar energy applications is equipped with six 200A separable insulated HV bushings, a dedicated neutral (H0) bushing, and resin-cast spade-type LV bushings featuring 12-hole terminals. The transformer’s protection system includes three bayonet fuses, current-limiting fuses (CLF), and elbow-type lightning arresters with metal oxide varistors that comply with IEEE 386 standards, ensuring robust surge and fault protection in dead-front configurations. Grounding pads installed on both HV and LV sides enhance installation safety and operational reliability. |
03 Testing
Routine Test and Testing Standard
- Resistance Measurements：According to IEEE C57.12.90-2021 Clause 5
- Ratio Tests：According to IEEE C57.12.90-2021 Clause 7
- Phase-relationTest：According to IEEE C57.12.90-2021 Clause 6
- No Load Losses and No Load Current：According to IEEE C57.12.90-2021 Clause 8
- Load Losses, Impedance Voltage and efficiency：According to IEEE C57.12.90-2021 Clause 9
- Applied Voltage Test：According to IEEE C57.12.90-2021 Clause 10.6
- Induced Voltage Withstand Test：According to IEEE C57.12.90-2021 Clause 10.5.1
- Insulation Resistance Measurement
- Leak Testing with Pressure for Liquid Immersed Transformers：The leaking test at 20KPa shall be conducted for 12h without leakage. No permanent deformatio
Test Results
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | Maximun resistance unbalance rate | 1.97 | Pass
|
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% Connection symbol: YNyn0 | -0.14% ~ 0.11% | Pass
|
| 3 | phase-relation tests | / | YNyn0 | YNyn0 | Pass
|
| 4 | No-load losses and excitation current | / | I0 :: provide measured value | 0.22% | Pass
|
| P0: provide measured value（t:20℃） | 2.200kW | ||||
| the tolerance for no load loss is +10% | / | ||||
| 5 | Load losses impedance voltage and efficiency | / | t:85℃ the tolerance for impedance is ±7.5% the tolerance for total load loss is +6% | / | Pass
|
| Z%: measured value | 5.88% | ||||
| Pk: measured value | 14.325kW | ||||
| Pt: measured value | 16.525 kW | ||||
| Efficiency not less than 99.52% | 99.52% | ||||
| 6 | Applied Voltage Test | kV | HV/: 34kV 60s LV/: 10kV 60s | No collapse of the test voltage occurs | Pass
|
| 7 | Induced Voltage Withstand Test | kV | Applied voltage (KV):2Ur | No collapse of the test voltage occurs
| Pass
|
| Duration(s):48 | |||||
| Frequency (HZ): 150 | |||||
| 8 | Leakage Test | kPa | Applied pressure：20kPA | No leakage and no Damage
| Pass
|
| Duration：12h | |||||
| 9 | Insulation Resistance Measurement | GΩ | HV-LV to Ground : | 2.01 | / |
| LV-HV to Ground: | 1.66 | ||||
| HV&LV to Ground | 1.03 |
04 Packing and Shipping
05 Site And Summary
This 2250 kVA three-phase pad-mounted transformer is specially designed for utility-scale solar PV projects in the U.S. market. It supports stable and safe power distribution with features that meet U.S. safety standards, ensuring reliable integration into solar farms and renewable energy systems.
Equipped with advanced insulation and cooling, it delivers efficient, eco-friendly performance ideal for clean energy applications. Robust protection components ensure safe operation in harsh outdoor environments.
Our transformers are engineered to meet the growing demands of the U.S. renewable energy sector. Contact us for tailored solutions to power your solar energy projects.
