Stable power, a smart choice – Three-Phase Pad-Mounted Transformer ensures energy efficiency and safety!
01 General
1.1 Project Description
A 75 kVA pad mounted transformer was delivered to America in 2024. The rated power of the transformer is 75 kVA with ONAN cooling. The primary voltage is 22.86GRDY/13.2kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.48y/0.208kV, they formed a vector group of YNyn0, and it is a loop feed and dead front transformer. The box body of the three phase pad mounted transformer produced by SCOTECH is mainly composed of a base, side panels, partitions, doors and top covers. The box is divided into high pressure chamber, a transformer chamber and low pressure chamber. High voltage chamber adopts perfect and reliable compact design, with a comprehensive anti-misoperation chain function, high reliability, easy maintenance, high voltage switchgear can be used terminal load switch, ring network switchgear and so on. The transformer room can be installed with an oil-immersed transformer or dry transformer, and is equipped with isolation protective net, the transformer room can adopt natural ventilation or forced ventilation, according to need to install an automatic temperature controller, room temperature monitoring and automatic ventilation device. The low-voltage chamber is equipped with distribution, metering, reactive power compensation and other standard schemes, and can design the secondary control loop and the number of wires according to the needs.
1.2 Technical Specification
75 kVA transformer specifications type and data sheet
| Delivered to | America |
| Year | 2024 |
| Type | Pad mounted transformer |
| Feed | Loop |
| Front | Dead |
| Standard | IEEE C57.12.34 |
| Rated Power | 75KVA |
| Frequency | 60HZ |
| Phase | 3 |
| Cooling Type | ONAN |
| Primary Voltage | 22.86GRDY/13.2 KV |
| Secondary Voltage | 0.48y/0.208 KV |
| Winding Material | Aluminum |
| Angular displacement | YNyn0 |
| Impedance | ≥2.7% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 0.28KW |
| On Load Loss | 1.07KW |
| Accessories | Standard Configuration |
1.3 Drawings
75 kVA pad mounted transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The three-phase five-column core consists of five columnar structures, usually three columns are used to carry the three-phase winding (phase A, B, C), while the other two columns serve as the connection and support structure. The magnetic circuit design of each column is designed to optimize the coupling and performance of the three-phase current. This design can effectively distribute and control the three-phase current and reduce the interference between phases. The arrangement of the five columns makes the possible leakage of the magnetic flux effectively controlled, and at the same time improves the permeability and efficiency of the core. Iron cores are often designed with symmetry in mind to achieve a uniform distribution of magnetic fields. The symmetrical design of the iron core can effectively reduce the loss caused by the magnetic field imbalance, and improve the working stability and electrical performance of the equipment. The three-phase winding can be evenly distributed on the three columns to form three interdependent magnetic fields. This layout ensures good flux linking and optimizes energy transfer. |  |
2.2 Winding
 | The use of high-conductivity aluminum can reduce the resistance of the winding, thereby reducing the line loss and improving the overall working efficiency of the transformer. The use of insulating materials can effectively prevent short circuit and leakage between windings and improve the operation efficiency of the transformer. The winding technology can ensure that the number of turns of the winding is reasonably evenly distributed, which can optimize the distribution of the magnetic field and improve the coupling efficiency of the transformer. Through reasonable design of the winding structure, the current can be evenly distributed in the winding, reducing local hot spots and reducing heating. By changing the number of turns of the winding, the voltage ratio of the transformer can be adjusted, so that it can be flexibly applied under different working conditions. The manufacturing process of wire wound technology is relatively mature, which can reduce the production cycle and manufacturing complexity, thus further reducing the cost. |
2.3 Tank
| High-quality stainless steel is selected as the fuel tank material to ensure the pressure resistance and corrosion resistance of the fuel tank. The steel plate is precisely cut according to the design drawings, usually using cutting machines, laser cutting or plasma cutting methods. The cut steel plate is polished, decontaminated and rust-proof to improve the welding quality and adhesion of the subsequent coating. The cut steel plate is folded and formed according to the design requirements for preliminary welding, usually using argon arc welding, CO₂ shielded welding or submerged arc welding and other welding processes. After the welding is completed, the weld is inspected, including visual inspection and ultrasonic inspection, to ensure the quality of the welding. Use high-quality sealing materials (such as rubber gaskets and sealants) at the joints and joints of the fuel tank to ensure the sealing performance of the fuel tank. Anti-rust treatment on the surface of the tank, usually using the bottom coating, and then spraying the top paint that meets the requirements of environmental protection to provide good anti-corrosion performance. |  |
2.4 Final Assembly
03 Testing
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | Maximum resistance unbalance rate≤5% | 1.16 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% | -0.04~-0.02 | Pass |
| 3 | phase-relation tests | / | YNyn0 | YNyn0 | Pass |
| 4 | No-load losses and excitation current | / | I0 :: provide measured value
| 0.33% | Pass |
| P0: provide measured value
| 0.062kW | ||||
| 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 | 3.65% | ||||
| Pk: measured value | 1.168kW | ||||
| Pt: measured value | 1.230kW | ||||
| Efficiency not less than 99.03% | 99.14% | ||||
| 6 | Applied Voltage Test | kV | LV: 10kV 60s | No collapse of the test voltage occurs | Pass |
| 7 | Induced Voltage Withstand Test | kV | Applied voltage (KV): 40 | 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 | LV-HV to Ground | 85.2 | / |
| 10 | Oil Test | / | Dielectric Strength; | 56.1 kv | Pass |
| Moisture Content | 9.7 mg/kg | ||||
| Dissipation Factor | 0.00327% | ||||
| Furan Analysis | 0.03 mg/kg | ||||
| Gas Chromatography Analysis | / |
04 Packing and Shipping
05 Site And Summary
The three phase 75 kVA pad mount transformer, with its excellent performance, reliable quality, and versatile applications, is the ideal choice for modern power distribution systems. Whether in commercial centers, industrial parks, or public infrastructure, this product efficiently meets various power needs, ensuring system stability and maximizing energy utilization. Choose the Three Phase Pad Mounted Transformer to make your power system more efficient and reliable, providing strong support for sustainable development in the future.
