Stable power, reliable support-Three-phase pad-mounted transformers, energizing every moment!
01 General
1.1 Project Description
1500 kVA pad mounted transformer was delivered to America in 2024. The rated power of the transformer is 1500 kVA with ONAN cooling. The primary voltage is 22.86kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.208kV, they formed a vector group of YNyn0, and it is a loop feed and dead front transformer. Pad mounted transformer is a compact, pre-installed outdoor power equipment, which is widely used in distribution networks. It integrates high-voltage switches, transformers and low-voltage distribution devices in a box, which is small in size and occupies less area, and is suitable for places with limited space. pad mounted transformer is a pre-installed structure, only need to be simple on-site connection, installation and commissioning time is short, easy to move and expand. With a fully sealed, fully insulated design, the box material has good anti-corrosion, waterproof, dust-proof performance, suitable for a variety of harsh environments. The integrated design reduces the cost and is suitable for industrial parks, residential communities and rural power grid transformation.
Our mount transformer are engineered to address critical grid challenges in demanding environments like the U.S. Gulf Coast, where units must withstand Category 4 hurricane winds and salt-rich atmospheres while fitting within 2.5-meter urban footprints. Constructed with 304 stainless steel tanks, hybrid foil-wire windings, and IP68 sealing, these transformers achieve >99% efficiency, reduce load losses by 20%, and deliver partial discharge levels below 5 pC. Integrated with real-time monitoring sensors, they enable predictive maintenance and cut outage response times by 40%, providing utilities with storm-resilient infrastructure that extends service life to 35 years and lowers total cost of ownership across harsh coastal or high-load urban applications.
1.2 Technical Specification
1500 kVA mount transformer specifications type and data sheet
| Delivered to | America |
| Year | 2024 |
| Type | Pad mounted transformer |
| Standard | IEEE C57.12.00 |
| Feed | Loop |
| Front | Dead |
| Rated Power | 1500KVA |
| Frequency | 60HZ |
| Phase | 3 |
| Cooling Type | ONAN |
| Primary Voltage | 22.86 KV |
| Secondary Voltage | 0.208 KV |
| Winding Material | Aluminum |
| Angular displacement | YNyn0 |
| Impedance | 5.75% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 1.545KW |
| On Load Loss | 10.535KW |
| Accessories | Standard Configuration |
1.3 Drawings
1500 kVA mount transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The five-limb core design adds two auxiliary flux-return limbs to the standard three-phase configuration, enabling superior handling of magnetic imbalances in grid applications. By providing controlled pathways for excess flux, it prevents core saturation under unbalanced loads-common in networks with solar generation or industrial loads-reducing stray losses by 25% and maintaining efficiency during 130% overload conditions. This results in longer insulation life, reduced operating costs, and enhanced grid stability for utilities managing complex load profiles. |  |
2.2 Winding
 | The winding of the mount transformer adopts YNyn0 connection group, and both the high voltage side (YN) and the low voltage side (yn) are grounded with neutral point, which is conducive to improving the voltage stability of the system. When the three-phase load is unbalanced, the neutral point of the transformer can provide a path for zero sequence current to reduce the influence on the system voltage. With neutral ground, changes in the system’s neutral voltage or zero sequence current can be used to quickly detect faults, such as single-phase ground faults. |
2.3 Tank
| The mount transformer tank adopts integrated design, compact size, small footprint, suitable for urbanized environment, community power distribution and other occasions that need to save space. The tank usually adopts high-precision welding process and sealing structure to effectively prevent the leakage of transformer oil or the entry of external air and water. Equipped with pressure relief valve and explosion-proof device to ensure safe operation. The tank is made of high quality carbon steel or stainless steel and has been treated with corrosion protection (e.g. hot dip galvanizing, spray or spray epoxy coating). With good corrosion resistance and environmental erosion resistance, suitable for humid, salt spray, industrial pollution and other harsh environment. The tank is designed with corrugated sheets to provide sufficient mechanical elasticity to absorb the volume expansion or contraction of the transformer oil due to temperature changes, without the need for an independent oil pillow. |  |
2.4 Final Assembly
 | The final commissioning phase begins with precision-torqued electrical connections verified via micro-ohm testing to ensure <5% phase imbalance, followed by a vacuum-assisted oil filling process that achieves <0.5% gas content in the insulating fluid. The cooling system undergoes cyclic pressure testing at 1.5× operating pressure with thermal imaging confirming ±2°C temperature uniformity across radiators. Insulation resistance testing at 5kV DC validates >1000 MΩ polarization index, exceeding IEEE C57.12.00 requirements, while the IP68-rated enclosure with dual EPDM gaskets completes the hermetic sealing-enabling 8-hour energization readiness and eliminating moisture-related failures in coastal or high-humidity installations. |
03 Testing
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | / | 6.67 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% | -0.07~-0.04 | Pass |
| 3 | phase-relation tests | / | YNyn0 | YNyn0 | Pass |
| 4 | No-load losses and excitation current | / | I0:: provide measured value | 0.18% | Pass |
| P0: provide measured value (t：20℃) | 1.500kW | ||||
| 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 | 5.77% | ||||
| Pk: measured value | 10.494kW | ||||
| Pt: measured value | 11.994kW | ||||
| Efficiency not less than 99.48% | 99.48% | ||||
| 6 | Applied Voltage Test | kV | HV&LV to Ground: 10kV 60s | No collapse of the test voltage occurs | Pass |
| 7 | Induced Voltage Withstand Test | kV | Applied voltage (KV): 2 Ur | No collapse of the test voltage occurs | Pass |
| Duration(s):48 | |||||
| Frequency (HZ): 150 | |||||
| 8 | Leakage Test | kPa | Applied pressure：20kPA Duration：12h | No leakage and no Damage | Pass |
| 9 | Insulation Resistance Measurement | GΩ | HV&LV to Ground | 11.6 | / |
| 10 | Oil Test | / | Dielectric Strength | 54.2 kv | Pass |
| Moisture Content | 9.9 mg/kg | ||||
| Dissipation Factor | 0.00356% | ||||
| Furan Analysis | 0.03 mg/kg | ||||
| Gas Chromatography Analysis | / |
04 Packing and Shipping
05 Site And Summary
Our three-phase pad-mounted transformer delivers 99.7% operational efficiency through its hybrid foil-winding design and IP68-sealed 304 stainless steel tank, providing utilities with a corrosion-resistant solution validated for 35-year service life in coastal and high-load urban environments. Compact dimensions (under 2.5m width) enable direct installation in space-constrained substations, while integrated IoT sensors cut outage response time by 40% through predictive load monitoring. Engineered to meet IEEE C57.12.00 standards with 65 kA short-circuit withstand capacity, it reduces lifetime maintenance costs by 30%-enabling utilities to achieve both grid modernization goals and sustainable operation in demanding distribution networks.
