The Heart of Your Power. Three-Phase Pad-Mount transformer, Built for Reliable Performance.
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 22.86GrdY/13.2 kV with ±2*2.5% tapping range (NLTC), the low voltage is 0.208/0.12 kV, they formed a vector group of YNyn0.
Three Phase Pad Mounted Transformer is a critical device in power distribution systems, widely applied in urban power grids, industrial facilities, commercial centers, and residential communities to provide stable and reliable power for various electrical equipment; its key specifications include a rated capacity of 1000 kVA, an efficiency of approximately 99.43% (meeting DOE 2016 standards to minimize energy loss), a no-load loss of 1095 W, a load loss of about 7094.84 W, aluminum winding material (which is cost-effective, lightweight, and optimized for electrical performance), and temperature parameters of 85℃ (reference temperature) and 55℃ (converted temperature, critical for operational safety and lifespan). It also boasts core advantages such as a compact design (small footprint with an integrated structure combining the transformer and HV/LV switchgear, suitable for space-constrained urban areas), strong protection (a high-quality steel cabinet with good corrosion resistance, dustproof, waterproof, and rodent-proof features), reliable operation (advanced insulation and heat dissipation design ensuring stable performance in harsh environments), and easy maintenance (rational component layout enabling quick inspection and repair), playing an irreplaceable role in modern power systems to guarantee safe, stable, and efficient power supply.
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 | 22.86GrdY/13.2 kV |
| Secondary Voltage | 0.208/0.12 kV |
| Winding Material | Aluminum |
| Vector Group | YNyn0 |
| Impedance | 5.75% |
| Efficiency | 99.43% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 1.095 kW |
| On Load Loss | 7.855 kW |
1.3 Drawings
1000 kVA pad mounted transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The core is made of highly permeable, cold-rolled silicon steel laminations. Its structure is a three-leg type, with the three-phase windings wound around the three vertical core legs respectively. This design provides a low-reluctance path for magnetic flux, enabling the effective conduction of the three-phase magnetic field. The lamination process and high-quality core materials are designed to minimize eddy current and hysteresis losses, thereby improving the transformer’s energy efficiency and operational performance. |  |
2.2 Winding
 | The windings of this transformer utilize aluminum for both the low-voltage foil and the high-voltage wire. The LV winding employs a wide aluminum foil, offering robust short-circuit strength and efficient cooling. The HV winding uses insulated aluminum wire, wound to achieve the necessary voltage rating. This all-aluminum design provides a cost-effective and reliable solution. |
2.3 Tank
| The tank is a sealed, corrugated steel enclosure that houses the core and windings while containing insulating oil. Its corrugated walls provide a large surface area for efficient heat dissipation to the ambient air, ensuring stable operation. Designed for durability and minimal maintenance, it offers full protection for the internal components. |  |
2.4 Final Assembly
 | The final assembly integrates the core-coil assembly, into a sealed corrugated steel tank and filled with insulating oil. Key components like HV/LV bushings, a pressure relief device, surge arrester and other accessories are mounted externally. This creates a completely self-contained, robust, and maintenance-friendly unit, ready for pad installation and grid connection. |
03 Testing
The three-phase pad mounted transformer (model: 1000KVA 22.86Grdy/13.2-0.208/0.12kV) was tested on October 19, 2024 (ambient temperature 34℃, relative humidity 73%) in accordance with standards such as IEEE C57.12.00-2021 and IEEE C57.12.34-2022. The tests included winding resistance measurement (maximum unbalance rate 5.51%), ratio test (main tap deviation -0.03~0.00%), phase-relation test (result YNyn0), no-load loss and current test (1016W at 20℃, 0.15% current), load loss, impedance voltage and efficiency test (7811W load loss at 85℃, 6.09% impedance, 99.45% efficiency), applied voltage test (10kV for LV to ground, 60s no breakdown), induced voltage withstand test (45.72kV induced at HV, 150Hz for 48s no breakdown), pressure leak test (20kPa for 12h no leakage/damage), insulation resistance measurement (16.5GΩ for HV&LV to ground), and oil dielectric test (56.3kV dielectric strength, 9.5mg/kg moisture), all of which passed.
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | / | 5.51 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% | -0.03~0.00 | Pass |
| 3 | phase-relation tests | / | YNyn0 | YNyn0 | Pass |
| 4 | No-load losses and excitation current | / | I0 :: provide measured value | 0.15% | Pass |
| P0: provide measured value(t:20℃) | 1.016kW | ||||
| 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 | 6.09% | ||||
| Pk: measured value | 7.811kW | ||||
| Pt: measured value | 8.827kW | ||||
| Efficiency not less than 99.43% | 99.45% | ||||
| 6 | Applied Voltage Test | kV | 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 | 16.5 | / |
| 10 | Oil Test | / | Dielectric Strength; | 56.3 kv | Pass |
| Moisture Content | 9.5 mg/kg | ||||
| Dissipation Factor | 0.00276% | ||||
| Furan Analysis | 0.03 mg/kg | ||||
| Gas Chromatography Analysis | / |
04 Packing and Shipping
4.1 Packing
| The three-phase pad mounted transformer is packaged by first placing a layer of tin foil bag on its tray, covering the transformer with the bag, putting desiccant inside, then sealing the bag (an opening is left to pump out gas with a vacuum cleaner first, followed by sealing the opening with a sealer); next, corner protectors (made of foam, plastic or cardboard) are added around the transformer and it is wrapped with protective film; finally, it is packed in a wooden box externally, which is sprayed with forklift markings and center of gravity markings. |  |
4.2 Shipping
 | The transformers are transported via sea freight from China to the United States. They are securely stowed inside standardized shipping containers, which provide protection from the harsh marine environment. During the voyage, the containers are carefully stacked and secured on large container ships. This method is the most cost-effective and reliable for moving such heavy and bulky equipment across the Pacific Ocean, ensuring the transformers arrive at US ports ready for onward delivery. |
05 Site And Summary
As a reliable cornerstone of modern power distribution networks, our three-phase pad-mounted transformer integrates efficient design, robust construction, and simplified maintenance. It not only ensures safe and stable power conversion but also serves as an ideal solution for your intelligent distribution management. We are committed to delivering product value that exceeds expectations, working together to build a more efficient and reliable electrical future.
