1500 KVA Transformer Mounting Pad-34.5/0.4 KV | USA 2025

Quiet, tamper-proof, and maintenance-friendly—pad mounted transformer delivers power where you need it.

01 General

1.1 Project Description

1500 kVA three phase pad mounted transformer was delivered to USA in 2025. The rated power of the transformer mounting pad is 1500 kVA with KNAN cooling. The high voltage is 34.5D kV with ±2*2.5% tapping range (NLTC), the low voltage is 0.4Y/0.23 kV, they formed a vector group of Dyn1.

SCOTECH offers this 1500 kVA pad-mounted transformer, designed and manufactured in compliance with IEEE Std C57.12.34-2022. Suitable for outdoor distribution applications (up to 1000m altitude), this dead-front, loop-feed capable unit delivers reliable performance for commercial, industrial, and utility networks.

Key Features

• Cooling System – KNAN with FR3® Oil

The transformer adopts a KNAN cooling method (natural convection of fluid and air), utilizing FR3 natural ester fluid. FR3 offers a high fire point (>300°C), 100% biodegradability, and superior moisture management, significantly extending insulation life compared to conventional mineral oil.

• High-Quality Fuses – Cooper Power Series

Equipped with Eaton Cooper Power series fuses: three Bay-O-Net expulsion fuses (4000380C14CB) and three ELSP current-limiting backup fuses (CBUC38140D100). This combination provides full-range fault protection, with easy field replacement of the Bay-O-Net fuse.

• DOE 2016 Efficiency Compliance

The transformer meets U.S. DOE 2016 efficiency standards, achieving 99.48% efficiency – reducing energy losses and operating costs while supporting energy conservation goals.

This transformer combines fire safety, environmental responsibility, robust protection, and high efficiency – a dependable solution for modern power distribution systems.

1.2 Technical Specification

1500 kVA transformer mounting pad specifications type and data sheet

1.3 Drawings

1000 kVA transformer mounting pad diagram drawing and size.

02 Manufacturing

2.1 Core

The transformer mounting pad core adopts a three-limb design, fully matching the 1500 kVA rating and Dyn1 vector group, and complies with IEEE C57.12.34-2022. Measured no‑load loss is only 1.395 kW (at 20°C) and no‑load current is as low as 0.13%, demonstrating excellent magnetic circuit efficiency and material quality. These results come from the routine test report (section 4.4), proving the core’s low loss and high reliability. Manufacturing uses high‑permeability, low‑loss grain‑oriented silicon steel with fully automatic stacking, ensuring consistent core rigidity and magnetic performance. Manufacturing highlights: high‑permeability material, automatic stacking, low‑hysteresis design.

2.2 Winding

The windings are aluminum, with rated voltages 34500‑400Y/230 V and tapping range ±2×2.5%, perfectly matching the design parameters. They comply with IEEE C57.12.90-2021 requirements for resistance unbalance, dielectric strength, and temperature rise. According to the test report, the maximum HV winding resistance unbalance is only 0.44% (well below the 4.88% limit). The applied voltage test passed at 50 kV (HV) and 10 kV (LV) for 60 seconds; the induced voltage test passed at 30.8 kV applied / 69 kV induced, 150 Hz for 48 seconds with no breakdown. Meanwhile, average winding temperature rise ≤65°C, hot‑spot rise ≤80°C, and top oil rise ≤65°C, ensuring long‑term safe operation. Quality is assured by automatic winding machines with constant tension control and inter‑turn insulation inspection. Manufacturing highlights: automatic winding, double‑layer insulation, high withstand voltage structure.

2.3 Tank

The tank is a sealed bolted‑cover design made of mild steel, equipped with lifting lugs and jacking pads, fully suitable for outdoor installation. Color and dimensions follow the final drawing (Munsell 9 GY 1.5/2.6 equipment green). It complies with IEEE C57.12.34 requirements for mechanical strength and corrosion protection. The leak test report shows that after applying 15 kPa pressure for 24 hours, there was no leakage or permanent deformation, confirming tank integrity. Quality assurance includes 100% weld inspection and a high‑corrosion‑resistance coating. Manufacturing highlights: welded bolted‑cover design, 24‑hour pressure leak test, high‑grade anti‑corrosion paint.

2.4 Final Assembly

Final assembly integrates six separable insulated HV bushings, three cast‑resin LV bushings, grounding lugs, a de‑energized tap changer, and – as a key project highlight – high‑quality Cooper fuses (bayonet type and current‑limiting back‑up). The assembly fully matches the drawings and complies with IEEE practices for clearances and mechanical interlocking. Insulation resistance measurements show: HV‑LV to ground 1.65 GΩ, LV‑HV to ground 1.58 GΩ, and HV&LV to ground 1.12 GΩ – far above typical safety thresholds, proving assembly reliability. Quality is ensured by using brand‑name Cooper components, traceable assembly records, and dual‑checking of critical torques. Manufacturing highlights: Cooper fuses, separable HV bushings, 100% insulation resistance verification.

03 Testing

All tests are performed according to IEEE C57.12.90-2021, covering ratio, losses, impedance, polarity, dielectric, and sealing. Test results perfectly match the guaranteed values: ratio deviation on the principal tapping is -0.08% to -0.07% (≤0.5% acceptable); measured impedance is 5.78% (tolerance ±7.5%); load loss at 85°C is 9.836 kW; total loss is 11.231 kW. Most importantly, the transformer achieves 99.52% efficiency – exceeding the DOE 2016 standard requirement of 99.48%, successfully meeting the project’s energy efficiency goal. All applied voltage, induced voltage, insulation resistance, and leak tests passed on the first attempt without any breakdown or leakage. Quality assurance is supported by an ISO/IEC 17025 accredited laboratory, regularly calibrated equipment, and automated data recording. Manufacturing highlights: full routine testing, third‑party standard alignment, measured efficiency better than DOE.

04 Packing and Shipping

4.1 Packing

Packing uses a reinforced steel‑wood structure suitable for overland or sea export. The transformer is shipped with nitrogen or FR3 oil inside to prevent moisture absorption. Packaging complies with IEC 60076‑10 and customer export specifications. Before packing, a final integrity check and pressure retention test are carried out to ensure no leakage risk. Desiccant and humidity indicator cards are included for additional reliability during transit. Quality assurance includes a final visual inspection and accessory checklist, plus bilingual manuals and test reports. Manufacturing highlights: steel‑wood reinforcement, nitrogen/oil‑filled protection, vibration and moisture‑proof design.

4.2 Shipping

Before shipping, the external dimensions and weight are confirmed against the final drawing to fit standard containers or flatbed trucks, fully matching the logistics plan. Shipping complies with international maritime dangerous goods regulations (if applicable) and customer customs documentation requirements. A final appearance check and accessory count are performed, accompanied by a complete test report, nameplate photo, and instruction manual. Shipping reliability is ensured by experienced heavy‑lift transformer logistics partners, with GPS tracking and full transit insurance. Manufacturing highlights: specialized heavy‑cargo experience, full traceability, complete documentation package.