Pad-Mounted Transformers: Where Safety Meets Simplicity.
01 General
1.1 Project Description
1000 kVA three phase pad mounted transformer was delivered to America in 2024. The rated power of the transformer is 1000 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.
The Pad-Mounted Transformer is a vital and reliable component of modern electrical distribution systems, designed to safely step down high voltage to the low voltage required by homes, businesses, and public facilities.
Encased in a locked, tamper-resistant steel enclosure, it is the cornerstone of underground power networks, perfectly suited for residential subdivisions, commercial areas, and urban landscapes where aesthetics and public safety are paramount. Its low-profile design minimizes visual impact while providing robust performance.
Key features include exceptional durability to withstand harsh environmental conditions, user-safe operation for utility personnel, and easy accessibility for maintenance. Engineered for long-term reliability and efficiency, the pad-mounted transformer delivers the quiet, uninterrupted power that communities depend on, making it the trusted link between the utility grid and the end-user.
1.2 Technical Specification
1000 kVA pad mounted transformer specifications type and data sheet
| Delivered to | USA |
| Year | 2024 |
| Type | Pad mounted transformer |
| Standard | IEEE Std C57.12.34-2022 |
| Rated Power | 1000 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 | 99.43% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 1.3 kW |
| On Load Loss | 6.94 kW |
1.3 Drawings
1000 kVA pad mounted transformer diagram drawing and size.
02 Manufacturing
2.1 Core
Our core uses high-grade grain-oriented silicon steel sheets and precision step-lap lamination. It cuts no-load loss by 15% vs industry average (slashing your electricity costs) and reduces noise/vibration (less maintenance). Strict pre-delivery testing ensures reliability, reflecting our strong R&D and manufacturing capability to meet your demand for efficiency and value. |  |
2.2 Winding
 | Get superior value with our aluminum-wound transformers. The HV foil and LV wire combination delivers proven reliability for your grid, directly reducing lifetime costs and outage risks. |
2.3 Tank
| The tank features an optimized cooling design that ensures lower operating temperatures. This directly extends the transformer’s service life and enhances overload capability, protecting your investment with proven, long-term performance. |  |
2.4 Final Assembly
 | Our transformers are designed for quick and simple installation. All internal and external components are pre-tested and pre-assembled as a complete, coordinated unit. This saves you significant time and labor costs during deployment while ensuring consistent, trouble-free operation throughout the product’s long service life. |
03 Testing
Our 1000kVA three-phase pad-mounted transformer (4160Δ-480Y/277V, serial 241204) stands out from competitors with IEEE-aligned (C57.12.00/34/90-2021/22) testing that delivers concrete, customer-focused results. Key metrics: 2.93% max winding resistance unbalance (avoids overheating, cuts maintenance), -0.13% voltage ratio deviation (ensures stable downstream power), 1.289kW no-load/7.223kW load losses (within ±10%/±6% tolerances for energy savings), 20.8-31.0GΩ insulation resistance (prevents electrical faults), 19kV HV/10kV LV withstand tests (60s, no voltage collapse for safety), 12-hour 20kPa leak-free testing (eliminates oil replacement costs), and 54.9kV oil dielectric strength (guarantees long-term insulation).
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | Maximum resistance unbalance rate | 2.93 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% | -0.13 | Pass |
| 3 | Phase-relation tests | / | Dyn1 | Dyn1 | Pass |
| 4 | No-load losses and excitation current | % | I0 :: provide measured value | 0.43 | Pass |
| kW | P0: provide measured value(85℃) | 1.289 | |||
| / | 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 | 5.42 | |||
| kW | Pk: measured value | 7.223 | |||
| kW | Pt: measured value | 8.451 | |||
| % | Efficiency not less than 99.43% | 99.43 | |||
| 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: | 20.8 | / |
| LV-HV to Ground: | 31.0 | ||||
| HV&LV to Ground: | 19.4 | ||||
| 9 | Leakage Test | / | Applied pressure: 20kPA | No leakage and no Damage | Pass |
| Duration: 12h | |||||
| 10 | Oil Test | kV | Dielectric Strength | 54.9 | Pass |
| mg/kg | Moisture Content | 9.7 | |||
| % | Dissipation Factor | 0.00227 | |||
| mg/kg | Furan Analysis | / | |||
| / | Gas Chromatography Analysis | / |
04 Packing and Shipping
4.1 Packing
For our three-phase pad-mounted transformers, packaging prioritizes your needs: vacuumed aluminum foil bags (with desiccants to prevent moisture damage) + corner protectors + labeled wooden crates (forklift/center-of-gravity marks). We skip no steps, so you get a rust-free, undamaged transformer with hassle-free on-site handling. |  |
4.2 Shipping
 | We provide a seamless, worry-free CIF service all the way to the Port of Los Angeles. Our expertise in transformer logistics and robust insurance coverage means we manage all transit risks and customs formalities. You benefit from a single point of accountability, ensuring a smooth, reliable delivery that protects your project timeline and investment. |
05 Site And Summary
Your distribution network demands a partner, not just a supplier. Our pad mounted transformers represent a complete solution, backed by our technical expertise and commitment to your success. We provide the tangible advantages you need: superior product design, seamless logistics, and unwavering support. Choose us for a partnership that de-risks your investment and delivers uncompromising value from specification to service.
