Stable voltage assurance and enhanced efficiency — the three-phase pad-mounted transformer makes power supply smarter!
01 General
1.1 Project Description
300 kVA pad-mounted transformer was delivered to USA in 2024. The rated power of the transformer is 300 kVA with ONAN cooling. The primary voltage is 34.5GrdY/19.92 kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.12/0.208 kV, they formed a vector group of YNyn0.
Three phase pad mounted transformers are commonly used in urban power distribution and industrial applications. The use of Load Break Connectors allows for the safe connection and disconnection of power while under load, enhancing operational safety and convenience. The pad-mounted transformer is connected to the grid and loads via underground cables. This design enhances safety and reduces the risks associated with overvoltage or short-circuit incidents. Pad mounted transformer is widely used in municipal power supply, commercial buildings, residential complexes, and industrial parks, providing stable power for various devices and facilities. The design of the pad-mounted transformer facilitates maintenance and is equipped with various safety measures, such as overload protection and short-circuit protection.
1.2 Technical Specification
300 KVA pad-mounted transformer specifications type and data sheet
| Delivered to | China |
| Year | 2024 |
| Type | Pad mounted transformer |
| Standard | ANSI Standard |
| Rated Power | 300 kVA |
| Frequency | 60HZ |
| Phase | 3 |
| Feed | Loop |
| Front | Dead |
| Cooling Type | ONAN |
| Primary Voltage | 34.5GrdY/19.92 kV |
| Secondary Voltage | 0.12/0.208 kV |
| Winding Material | Aluminum |
| Angular displacement | YNyn0 |
| Impedance | 5%(±7.5%) |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 0.46KW |
| On Load Loss | 4.675KW |
| Accessories | Standard Configuration |
1.3 Drawings
300 kVA pad-mounted transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The transformer core is a key component of the transformer, whose primary function is to provide a low-loss magnetic path to enhance the electromagnetic performance of the transformer. The core is typically made up of many thin laminated sheets of iron, a structure designed to reduce eddy current losses. These sheets are usually made of silicon steel, which has high magnetic permeability and good insulation properties. The design of the transformer core not only affects the efficiency of the transformer but also impacts its capacity and stability. During operation, the core generates a magnetic field through alternating current, enabling energy transmission and conversion. |  |
2.2 Winding
 | Based on the input and output voltage requirements of the transformer, calculate the turns ratio for the primary and secondary windings. The design of the turns ratio directly affects the transformer’s voltage ratio and power conversion. Use automatic winding machines to ensure uniformity and consistency of the windings. It is essential to ensure that the arrangement of the winding is tight and without crossings. Add isolation materials between different layers to ensure the insulation performance between layers. |
2.3 Tank
| The oil tank is made of steel materials and undergoes anti-corrosion treatment, with the outer surface coated with rust-resistant paint. Its shape is rectangular, designed to ensure load-bearing capacity and stability to withstand external environmental pressures. The oil tank is filled with insulating oil, which serves to cool and insulate. During operation, the oil absorbs heat generated by the windings and core, and dissipates heat through natural convection or forced circulation. The tank is designed with good sealing properties to prevent environmental pollution and oil leakage, and is equipped with safety valves, pressure gauges, and other devices to ensure safe operation. |  |
2.4 Final Assembly
 | Component Preparation: Ensure that key components such as the transformer core, windings, and oil tank are ready. Assemble the Oil Tank: Fix the treated steel oil tank in place and install sealing gaskets to prevent oil leakage. Install Core and Windings: Place the transformer core inside the oil tank and install the windings, ensuring proper alignment and secure fastening. Connect Cables: Connect the high-voltage and low-voltage cables, using insulating materials to ensure safety. Fill with Oil and Vent: Fill the oil tank with insulating oil, removing air and ensuring oil quality. |
03 Testing
(1) Routine test
a) Ratio on connections and tap positions
b) Angular displacement
c) No-load losses at 100% rated voltage
d) Exciting current at 100% rated voltage
e) Load losses and impedance at rated current
f) Applied voltage
g) Induced voltage
h) Transformer tank leak-detection test
i) A continuity test
(2) Type test
a) Resistance
b) Temperature rise
c) Impulse strength
d) Radio-influence voltage
f) Transformer integrity
g) Core audible sound
h) Negative pressure withstand
04 Packing and Shipping
05 Site And Summary
In conclusion, the three-phase pad-mounted transformer plays a pivotal role in modern electrical distribution systems, offering reliability and efficiency in power delivery. Its robust design and advanced technology ensure optimal performance while minimizing energy losses and environmental impact. Through rigorous testing and quality assurance processes, these transformers are built to withstand demanding conditions and provide safe, dependable service over their operational lifespan. As we continue to evolve in our energy needs, the three-phase pad-mounted transformer stands as a crucial component in advancing our power infrastructure, supporting the transition to more sustainable energy solutions for the future.
