Reliable and efficient 50 kVA pole-mounted transformer, engineered for North American distribution networks with superior performance
01 General
1.1 Project Description
The 50 kVA single-phase pole-mounted transformer has a 13.8 kV primary and 120/240 V secondary. Designed to IEEE C57.12.20 for overhead distribution transformers. It is suitable for 13.8 kV three-phase, three-wire distribution networks in North America. The 50 kva pole mount transformer features ONAN natural oil cooling with mineral oil insulation. With a focus on efficiency and space optimization, Scotech utilizes both aluminum and copper winding. The polarity is subtractive, and the vector group is Ii0, ensuring correct phase sequence in the distribution network. Performance highlights include a no-load loss of 0.14 kW, load loss of 0.527 kW, total losses of 0.667 kW, and full-load efficiency of 98.97%. Impedance is 2.86%, within typical distribution transformer ranges. Additionally, the transformer is equipped with a no-load tap changer (NLTC) allowing high-voltage adjustment from 14, 400 V to 12, 540 V to accommodate voltage fluctuations in the network.
1.2 Technical Specification
50kVA single phase pole mounted transformer specification and data sheet
| Delivered to | North_America |
| Year | 2025 |
| Type | Pole Mounted Transformer |
| Standard | IEEE C57.12.20 |
| Rated Power | 50 kVA |
| Frequency | 60HZ |
| Phase | single |
| Cooling Type | ONAN |
| Liquid insulant | Mineral Oil |
| Primary Voltage | 13.8 kV |
| Secondary Voltage | 0.12/0.24 kV |
| Vector Group | Ii0 |
| Polarity | Subtractive |
| Winding Material | HV:Copper, LV:Aluminum |
| Efficiency | 98.97 % |
| Impedance | 2.86% |
| Tap Changer | NLTC |
| Tapping Range | 14400,13800,13200,12870,12540 |
| No Load Loss | 0.14 kW |
| On Load Loss | 0.527 kW |
| Accessories | Standard Configuration |
1.3 Drawings
50kVA single phase pad mounted transformer diagram drawing and size.
02 Manufacturing
2.1 Core
Using grain-oriented silicon steel, the wound core provides excellent magnetic performance by minimizing distortion in the flux path. The design avoids magnetic saturation, ensuring stable operation under load variations. Compared to traditional stacked cores, the wound structure lowers no-load loss and no-load current, while also reducing vibration and noise. These advantages make the wound core highly energy-efficient and reliable in distribution systems.
2.2 Winding
 | The high voltage winding adopts concentric construction with electrolytic copper wire of 99.9% purity, enamel insulated, ensuring conductivity not less than 100% IACS. Thermal insulation withstands up to 105°C. LV winding uses aluminum foil, which minimizes eddy current losses, ensures strong mechanical integrity, and meets utility distribution requirements. |
2.3 Tank
| The transformer tank is a sealed cylindrical structure made of mild steel with surface coating in RAL7035 color. It is designed without inspection or maintenance holes to ensure integrity. A removable domed cover is used for access. Mounting brackets are made of steel with a minimum thickness of 3.4 mm. The ends are bent and welded to the tank body. This makes the structure strong and durable. |  |
2.4 Final assembly
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2.5 Pole Mounted Transformer Parts
03 Testing
Testing Standard and Routine Test
IEEE C57.12.20-2017: IEEE Standard for Overhead-Type Distribution Transformers 500 kVA and Smaller; High Voltage,34500 V and Below; Low Voltage,7970/13 800Y V and Below
IEEE C57.12.90-2021: IEEE Standard Test Code for Liquid-Immersed Distrbution, Power, and regulating Transformers
CSA C802.1-13（R2022）: Minimum efficiency values for liquid-filled distribution transformers
- Resistance Measurements
- Ratio Tests
- Polarity Test
- No Load Losses and No Load Current
- Load Losses and Impedance Voltage
- Applied Voltage Test
- Induced Voltage Withstand Test
- Insulation Resistance Measurement
- Leak Testing with Pressure for Liquid Immersed Transformers
- Oil Dielectric Test
Test Results
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | / | / | / | Pass |
| 2 | Ratio Tests | / | The deviation of voltage ratio on the principal tapping: ≤0.5% Connection symbol: Ii0 | -0.02 | Pass |
| 3 | Polarity tests | / | Subtractive | Subtractive | Pass |
| 4 | No-load losses and excitation current | % kW | I0 :: provide measured value P0: provide measured value the tolerance for no load loss is +10% | 0.22 0.107 | Pass |
| 5 | Load losses , impedance voltage,total losses and efficiency | / kW kW | t:85℃ Z%: measured value Pk: measured value Pt: measured value the tolerance for impedance is ±10% the tolerance for total load loss is +6% | 2.93 0.557 0.664 99.07 | Pass |
| 6 | Applied Voltage Test | / | HV：30KV 60s LV: 10kV 60s | No collapse of the test voltage occurs | Pass |
| 7 | Induced Voltage Withstand Test | / | Applied voltage (KV): 2 Ur Duration(s): 48 Frequency (HZ): 150 | No collapse of the test voltage occurs | Pass |
| 8 | Insulation Resistance Measurement | GΩ | HV-LV to Ground LV-HV to Ground HV&LV to Ground | 96.9 49.1 55.8 | Pass |
| 9 | Leakage Test | / | Applied pressure：20kPA Duration：12h | No leakage and no Damage | Pass |
| 10 | Oil Dielectric Test | kV | ≥45 | 59.1 | Pass |
04 Packing and Shipping
05 Site And Summary
The 50 kVA single-phase pole-mounted transformer works for North American overhead distribution networks. It uses ONAN oil cooling and runs efficiently. The core is made of wound silicon steel. The windings use good copper and aluminum. This gives stable voltage, low losses, and quiet operation. It has a no-load tap changer for voltage adjustment. The tank is strong and sealed. It works well for homes and businesses. Scotech makes each transformer carefully. Every unit meets international standards.
