Pad-Mounted Transformers: The Modern Standard for Distributed Power.
01 General
1.1 Project Description
1000 kVA three phase pad mounted transformer was delivered to America in 2024. The rated power of the transformers electrical box is 1500 kVA with ONAN cooling. The high voltage is 4.16D kV with ±2*2.5% tapping range (NLTC), the low voltage is 0.48Y/0.277 kV, they formed a vector group of Dyn1.
Engineered for reliability and safety in electrical distribution networks, our Pad-Mounted Transformer is a cornerstone of modern underground power systems. Designed for seamless integration into residential, commercial, and industrial landscapes, it delivers robust performance while prioritizing public safety and aesthetic discretion.
A key feature contributing to its exceptional durability and long-term reliability is the use of high-voltage porcelain bushings. Renowned for their superior mechanical strength, excellent dielectric properties, and proven resistance to environmental degradation, these porcelain bushings ensure a secure and stable connection point for medium-voltage cables. Their robust construction provides outstanding performance under varying thermal and electrical stresses, guaranteeing integrity over decades of service.
Encased within a tamper-resistant, locked steel enclosure, this transformers electrical box combines the operational excellence of time-tested materials like porcelain with advanced core and coil technology. It stands as a secure, low-profile, and highly dependable solution for efficiently stepping down power from the utility grid to the end-user.
1.2 Technical Specification
1500 kVA transformers electrical box specifications type and data sheet
| Delivered to | USA |
| Year | 2024 |
| Type | Pad mounted transformer |
| Standard | IEEE Std C57.12.34-2022 |
| Rated Power | 1500 kVA |
| Frequency | 60HZ |
| Phase | 3 |
| Feed | Loop |
| Front | Dead |
| Cooling Type | ONAN |
| Primary Voltage | 4.16D kV |
| Secondary Voltage | 0.48Y/0.277 kV |
| Winding Material | Aluminum |
| Vector Group | Dyn1 |
| Impedance | 5.75% |
| Efficiency | 99.48% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 1.545 kW |
| On Load Loss | 10.54 kW |
1.3 Drawings
1500 kVA transformers electrical box diagram drawing and size.
02 Manufacturing
2.1 Core
| Our core reduces no-load losses by 70%, delivering maximum energy savings and lower lifetime costs for superior ROI. Built for reliability and quiet operation, it’s the smarter long-term investment. |  |
2.2 Winding
 | Our pad mounted transformers feature reliable aluminum foil HV and wire LV windings. This design ensures robust short-circuit strength and thermal performance, giving you maximum uptime at a lower cost than copper alternatives. |
2.3 Tank
| Our tank is made of seamless, corrosion-resistant steel, rigorously tested to guarantee a leak-proof seal for life. This eliminates maintenance worries and costly environmental cleanup, providing total reliability and lower long-term costs. |  |
2.4 Final Assembly
 | The final assembly of our pad-mounted transformers integrates core, coils, and tank with precision alignment and proven processes. This ensures optimal performance, minimized noise and vibration, and long-term structural integrity. You receive a transformer that operates quietly and reliably from day one, backed by our rigorous quality controls and extensive field experience. |
03 Testing
For our 1500kVA three-phase pad-mounted transformer (4160Δ-480Y/277V), testing focuses on your priorities: low cost, no downtime. We share clear data: 2.83% winding unbalance (avoids overheating), -0.23%~0.15% turns ratio (stable power), 18.2-18.6GΩ insulation (fewer faults), 12h leak-free (no oil costs), 56.4kV oil strength (safe operation), and 99.48% efficiency (energy savings). All metrics meet guarantees.
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | Maximum resistance unbalance rate | 2.83 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% | -0.12 | Pass |
| 3 | Phase-relation tests | / | Dyn1 | Dyn1 | Pass |
| 4 | No-load losses and excitation current | % | I0 :: provide measured value | 0.26 | Pass |
| kW | P0: provide measured value(20℃) | 1.567 | |||
| / | the tolerance for no load loss is ±10% | / | |||
| 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 ±6% | / | Pass |
| % | Z%: measured value | 5.67 | |||
| kW | Pk: measured value | 10.475 | |||
| kW | Pt: measured value | 12.042 | |||
| % | Efficiency not less than 99.48% | 99.48 | |||
| 6 | Applied Voltage Test | / | HV: 19kV 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):48 | |||||
| Frequency (HZ): 150 | |||||
| 8 | Insulation Resistance Measurement | GΩ | HV-LV to Ground: | 18.2 | / |
| LV-HV to Ground: | 18.6 | ||||
| HV&LV to Ground: | 18.5 | ||||
| 9 | Leakage Test | / | Applied pressure: 20kPA | No leakage and no Damage | Pass |
| Duration: 12h | |||||
| 10 | Oil Test | kV | Dielectric Strength | 56.4 | Pass |
| mg/kg | Moisture Content | 9.9 | |||
| % | Dissipation Factor | 0.00247 | |||
| mg/kg | Furan Analysis | / | |||
| / | Gas Chromatography Analysis | / |
04 Packing and Shipping
4.1 Packing
| Our three-phase pad-mounted transformers use dual protection: first vacuum-sealed in aluminum foil bags with desiccants (stops rust, a common issue competitors ignore), then wrapped with corner protectors and packed in sturdy wooden crates. Unlike others’ unmarked crates, ours has forklift/center-of-gravity labels for easy handling-ensuring your transformer arrives intact, ready to use. |  |
4.2 Shipping
 | Under our CIF terms to the Port of Los Angeles, we assume full responsibility for the cost, insurance, and freight of your shipment. Our partnerships with top-tier carriers and meticulous logistics planning ensure your transformer arrives on time and in perfect condition. This eliminates the complexity and risks of international shipping for you, providing cost certainty and peace of mind. |
05 Site And Summary
When you specify our three-phase pad mounted transformers, you are selecting more than just a product – you are investing in decades of reliable performance. From the robust aluminum windings and leak-proof tank to the secure packaging and managed delivery, every detail is engineered to minimize your lifetime costs and operational risks. We deliver proven reliability that keeps your projects on schedule and your community powered, year after year.
