Quiet operation, fully enclosed protection — the pad-mounted transformer hides safety and durability behind its unassuming appearance.
01 General
1.1 Project Description
1000 kVA transformer 1000kVA was delivered to USA in 2025. The rated power of the transformer 1000kVA is 1000 kVA with KNAN cooling. The high voltage is 13.8D kV with ±2*2.5% tapping range (NLTC), the low voltage is 0.6Y/0.346 kV, they formed a vector group of Dyn1.
This pad-mounted transformer is a 1000 kVA, three-phase, three-leg unit engineered for reliable performance in underground distribution networks. Designed with a loop-feed configuration and dead-front construction, it ensures operational safety and service continuity by minimizing exposed live parts and enabling flexible system interconnection. The transformer utilizes FR3 vegetable oil, providing superior fire safety, enhanced biodegradability, and improved insulation life compared to conventional mineral oil. Meeting DOE efficiency standards, this unit delivers low core losses and high operational economy. It is factory-equipped with surge arresters for integrated overvoltage protection, and finished with a durable powder-coated white (RAL 9003) enclosure that combines corrosion resistance with a clean, aesthetically neutral appearance suitable for residential or commercial applications.
1.2 Technical Specification
1000 kVA transformer 1000kVA specifications type and data sheet
| Delivered to | USA |
| Year | 2025 |
| Type | Pad mounted transformer |
| Standard | IEEE Std C57.12.34-2022 DOE 2016 |
| Rated Power | 1000 kVA |
| Frequency | 60HZ |
| Phase | 3 |
| Feed | Loop |
| Front | Dead |
| Cooling Type | KNAN |
| Primary Voltage | 13.8D kV |
| Secondary Voltage | 0.6y/0.346 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 transformer 1000kVA diagram drawing and size.
02 Manufacturing
2.1 Core Design & Performance
Adopts a 3-leg three-phase core made of high-permeability, low-loss silicon steel sheet (60Hz rated frequency). The measured no-load current is only 0.54%, ensuring low-loss and high-efficiency operation of the magnetic circuit.
Multi-dimensional Assurance
- Parameter Matching: Core design fully matches 1000kVA rated capacity and KNAN self-cooling mode, meeting the temperature rise requirements (average ≤65℃, hottest-spot ≤80℃).
- Standard Compliance: Follows IEEE Std C57.12.34-2022 for magnetic circuit design and loss control.
- Quality Guarantee: Raw materials 100% inspected; lamination with precision tooling; magnetic performance pre-test for each core; non-conforming products rejected in the early process.
2.2 Winding
 | Uses high-quality aluminum windings with ±2*2.5% no-load tap changing. The measured resistance unbalance rate is 0.13% (HV) / 2.43% (LV), and voltage ratio deviation is -0.01%~0.06%, with excellent consistency and voltage conversion accuracy. Quality Guarantee: CNC winding process; insulation/resistance test after winding; passed pressure resistance and temperature rise tests with no breakdown or overheating. |
2.3 Tank
Made of high-quality carbon steel with a sealed structure and bolted cover, equipped with lifting lugs and jacking pads for easy handling. Surface sprayed with RAL 9003 white powder for corrosion resistance; tested 24h at 20kPa with no leakage, excellent sealing performance.
Multi-dimensional Assurance
Project Application: Sealed and anti-corrosion design for outdoor open-air installation (altitude ≤1000m), applicable to municipal infrastructure and industrial park power distribution.
Parameter Matching: Tank volume/structural strength fully matches FR3 oil filling amount and transformer total weight (no oil spill or deformation risk).
Quality Guarantee: Precision machining for bending/welding; non-destructive testing for welds; pickling and phosphating before spraying; separate HV/LV compartments for higher insulation reliability.
2.4 Final Assembly
Adopts loop feed design; HV compartment with 6 separable insulated bushings (200A), LV compartment with 3 resin cast bushings. Standard configuration: 3 bayonet fuses, 3 CLFs, 1 four-position load break switch, 1 no-load tap changer, and full monitoring instruments (oil thermometer, level gauge, etc.). 3 sets of lightning arresters for integrated power distribution, protection and monitoring.
Multi-dimensional Assurance
- Parameter Matching: Rated current/voltage of all accessories match transformer core parameters; lightning arrester grade adapts to transformer BIL (30kV HV / 95kV LV).
- Standard Compliance: Assembly process, wiring and grounding terminal design (1 each in HV/LV) follow IEEE Std C57.12.34-2022.
- Quality Guarantee: Standardized assembly process; continuity/insulation test after wiring; no-load test for the whole machine; full-process inspection to ensure assembly accuracy.
03 Testing
1. Standard Compliance
Test process designed in accordance with IEEE Std C57.12.34-2022; energy efficiency tested per DOE 2016 standard (all results meet and exceed requirements).
2. Core Test Results (Measured Values)
| Test Item | Standard/Guaranteed Value | Measured Value | Conclusion |
| Winding Resistance Unbalance | ≤5% (industry conventional) | 0.13% (HV) / 2.43% (LV) | Pass |
| Voltage Ratio Deviation | ≤0.5% (rated tap) | -0.01% ~ 0.06% | Pass |
| No-load Loss (20℃) | ≤1.3kW (+10% tolerance) | 1.214kW | Pass |
| No-load Current | Judged by measured value | 0.54% | Pass |
| Load Loss (85℃) | ≤6.94kW (+6% tolerance) | 6.502kW | Pass |
| Short-circuit Impedance | ±7.5% tolerance (5.75%) | 5.74% | Pass |
| Overall Efficiency | ≥99.43% (DOE 2016) | 99.47% | Pass |
| Applied Voltage Test | 34kV (HV)/10kV (LV), 60s no collapse | No voltage collapse | Pass |
| Induced Voltage Test | 2Ur, 150Hz, 48s no collapse | No voltage collapse | Pass |
| Leakage Test | 20kPa, 24h no leakage | No leakage & no damage | Pass |
| Insulation Resistance | Judged by measured value | 1.87GΩ (HV-LV to GND);2.54GΩ (LV-HV to GND);1.26GΩ (HV&LV to GND) | Pass |
04 Packing and Shipping
4.1 Packing
| Inner layer: Vacuum aluminum foil bag, containing desiccant, for moisture and rust prevention; Outer layer: Wooden box, with forklift marking and center of gravity marking sprayed on it; Edge protection materials: foam, plastic or cardboard edge guards to prevent damage during transportation; Suitable for sea transportation and long-term outdoor storage. |  |
4.2 Shipping
 | The outer packaging of the wooden box is clearly marked: Forklift operation position Center of gravity position The overall weight, oil weight and dimensions of the transformer are detailed in the drawings. Export packaging declarations and packing lists can be provided. |
05 Site And Summary
This is a transformer 1000kVA that fully complies with IEEE and DOE standards, has superior actual performance compared to its value, uses FR3 environmentally friendly oil, and has lightning arrester protection capabilities. It has passed all routine tests, with reliable test results, controllable manufacturing process, standardized packaging and transportation, and is suitable for ground distribution projects in the North American market.
