1500 KVA Electrical Transformer Box-12.47/4.16 KV | USA 2025

An advanced electrical transformer box engineered to meet IEEE and UL standards, ensuring efficient and secure power distribution

01 General

1.1 Project Description

The 1.5 MVA (1500 kVA) three-phase pad-mounted transformer gives reliable, utility-grade power in a compact, tamper-resistant enclosure. It is built to meet IEEE Std C57.12.34-2022, DOE 2016, and UL Listed standards. It offers a safe and efficient solution for medium-voltage distribution systems and comes with a 3-year warranty for long-term reliability.

The transformer has a loop-feed and dead-front design. It changes the voltage from 12.47 kV on the primary side to 4.16 kV on the secondary side with a Dyn1 vector group. This setup works well for many network types. It has five off-circuit tap positions (14.4 kV, 13.8 kV, 13.2 kV, 12.47 kV, 12.0 kV) to adjust the voltage as needed on site. It uses ONAN cooling and mineral oil insulation. The temperature rise is 65 °C. These features keep the transformer stable and extend its service life.

Its aluminum windings provide a balance of durability and cost efficiency, while a 5.75% impedance supports reliable fault management. Tested for DOE 2016 losses-no-load loss of 1,545 W and load loss of 10,540 W-the design meets energy-efficiency targets and reduces operating costs. Standard accessories include a bayonet fuse with isolation links and a three-piece, two-position load break switch.

These parts make protection simple and operation safe.

The transformer is compact, reliable, and easy to maintain. It is a good choice for utility distribution systems, renewable energy sites, industrial facilities, and infrastructure power networks in America (2025 delivery).

1.2 Technical Specification

1500kVA three phase pad mounted transformer specification and data sheet

1.3 Drawings

1500kVA three phase pad mounted transformer diagram drawing and size

02 Manufacturing

2.1 Core

The 1500 KVA electrical transformer box core has a three-limb, step-lap mitered design. It is made of grain-oriented, cold-rolled silicon steel. Each lamination is cut with precision and has no burrs. This helps lower core loss and reduce noise. The laminations are stacked and clamped tightly to avoid air gaps. This improves magnetic performance and keeps the transformer efficient and reliable.

2.2 Winding

The transformer has wire-wound high-voltage primary coils and sheet-wound secondary coils. This design reduces axial stress caused by short circuits and allows balanced magnetic distribution across tap connections. Coils are made with high-precision winding machines that ensure consistent tension and accurate conductor placement, giving the transformer strong short-circuit resistance and high efficiency.

2.3 Three Independent Load Break Switches

The electrical transformer box is equipped with three independent two-position load break switches, providing flexible phase-by-phase switching capability for medium-voltage distribution systems. Compared with conventional gang-operated switch designs, the three-switch configuration allows selective phase isolation during maintenance or fault conditions, reducing unnecessary outages and improving system reliability.

2.4 Tank

The transformer tank is made of mild steel. It is strong and easy to handle, install, and maintain. The tank has a sealed bolted cover to protect the insulating fluid and internal parts. The steel is precision-cut, hot-rolled, pickled, and oiled. The welding ensures the tank is durable and reliable.

2.5 Final Assembly

The pad-mounted transformer core and coil assembly is braced with heavy steel ends to keep the rectangular coils from bending during short-circuit conditions. The plates are clamped tightly with presses and then welded or bolted to form a solid structure. The assembly meets or exceeds ANSI and IEEE short-circuit standards. The rigid design keeps impedance shift small, similar to circular-wound coils.

03 Major Components

04 Testing

05 Packing and transportation