Powering reliability with safety, efficiency, and durability - Scotech pad-mounted transformers built for today's energy demands
01 General
1.1 Project Description
The 500 kVA three-phase pad-mounted transformer, delivered to the USA in 2024, is manufactured to meet IEEE Std C57.12.34-2022 and DOE 2016 efficiency standards.
Operating at 60 Hz, it features a primary voltage of 24 kV and a secondary voltage of 480GrdY/277 V with a Dyn1 vector group. The utility pad mounted transformer uses copper windings and KNAN cooling, filled with FR3 natural ester oil for improved fire safety and environmental compliance. It includes loop feed capability, dead-front access, and a no-load tap changer with a ±2 × 2.5% voltage adjustment range. With an impedance of 5.75%, no-load loss of 0.610 kW, and on-load loss of 4.530 kW, this unit delivers efficient and reliable medium-voltage power distribution. It is ideal for use in commercial complexes, small industrial sites, and residential developments where safe, consistent, and efficient power transformation is required.
1.2 Technical Specification
500kVA utility pad mounted transformer specification and data sheet
| Delivered to | USA |
| Year | 2024 |
| Type | Three phase pad mount transformer |
| Standard | IEEE Std C57.12.34-2022 |
| Rated Power | 500KVA |
| Frequency | 60HZ |
| Feed | Loop |
| Front | Dead |
| Phase | three |
| Cooling Type | KNAN |
| Liquid insulant | FR3 Oil |
| Primary Voltage | 24 Kv |
| Secondary Voltage | 0.48 Kv |
| Vector Group | Dyn1 |
| Winding Material | Copper |
| Impedance | 5.75% |
| Efficiency and Losses Standard | DOE 2016 |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 0.610 KW |
| On Load Loss | 4.530 KW |
| Accessories | Standard Configuration |
1.3 Drawings
500kVA utility pad mounted transformer dimensions and weight details
02 Manufacturing
2.1 Core
| SCOTECH transformer cores are made from high-grade imported cold-rolled silicon steel. Using in-house precision shearing lines, burrs are controlled below 0.02 mm. The cores feature fully mitered joints with no punching or stacked yokes, improving magnetic performance and reducing energy losses. |  |
2.2 Winding
 | This 500 kVA transformer features copper or aluminum foil windings on the LV side, offering even current distribution and strong short-circuit resistance. The HV side uses enamel-coated wire in a multi-layer structure, providing solid insulation and stable performance at 24 kV. |
2.3 Tank
| The transformer tank is a sealed steel structure that houses the core, windings, and insulating oil. Designed for strength and durability, it protects internal components from moisture, contaminants, and mechanical damage, ensuring safe operation and long service life. |  |
2.4 Final assembly
 | Scotech applies high-durability coatings to all transformer surfaces. After installation and cleaning, any scratches or finish damage should be touched up using matching protective paint provided or specified by Scotech, maintaining both corrosion resistance and aesthetic consistency. |
03 Testing
Routine Test and Testing Standard
1. Resistance Measurements according to IEEE C57.12.90-2021 Clause 5
2. Phase-relation Test according to IEEE C57.12.90-2021 Clause 6
3. Ratio Tests according to IEEE C57.12.90-2021 Clause 7
4. No Load Losses and No Load Current according to IEEE C57.12.90-2021 Clause 8
5. Load Losses, Impedance Voltage and Efficiency according to IEEE C57.12.90-2021 Clause 9
6. Induced Voltage Withstand Test according to IEEE C57.12.90-2021 Clause 10.5.1
7. Applied Voltage Test according to IEEE C57.12.90-2021 Clause 10.6
8. Leak Testing with Pressure for Liquid Immersed Transformers – the leaking test at 15 kPa shall be conducted for 12 h without leakage. No permanent deformation.
9. Insulation Resistance Measurement
10. Oil Dielectric Test
Test Results
| No. | Test Item
| Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | Maximum resistance unbalance rate | 0.171 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% Connection symbol: Dyn1 | 0.03% ~ 0.05% | Pass |
| 3 | phase-relation tests | / | Dyn1 | Dyn1 | Pass |
| 4 | No-load losses and excitation current | % kW | I0 :: provide measured value P0: provide measured value the tolerance for no load loss is +0% | 0.13% 0.544 | Pass |
| 5 | Load losses impedance voltage and efficiency | % kW kW | t:85℃ Z%: measured value Pk: measured value Pt: measured value the tolerance for impedance is ±7.5% the tolerance for total load loss is +0% Efficiency not less than 99.35%
| 5.70% 4.453 4.997 99.38% | Pass |
| 6 | Applied Voltage Test | kV | HV: 40kV 60s LV: 10kV 60s | No collapse of the test voltage occurs | Pass |
| 7 | Induced Voltage Withstand Test | kV | Applied voltage (KV): 0.960 Duration(s):40 Frequency (HZ): 180 | No collapse of the test voltage occurs | Pass |
| 8 | Leakage Test | kPa | Applied pressure：15kPA Duration：12h | No leakage and no Damage | Pass |
| 9 | Insulation Resistance Measurement | GΩ | HV-LV to Ground: LV-HV to Ground: HV&LV to Ground: | 5.11 4.87 5.08 | / |
| 10 | Oil Dielectric Test | kV | ≥40 | 52.3 | Pass
|
04 Packing and Shipping
05 Site And Summary
Scotech’s 500 kVA three-phase pad-mounted transformer built with copper windings and KNAN cooling, the transformer uses FR3 natural ester oil-improving fire safety and reducing environmental impact. Its loop-feed configuration and dead-front design enhance safety and flexibility for installation and maintenance. With an impedance of 5.75% and low energy losses, it ensures stable, efficient performance across demanding conditions.
Every Scotech transformer is assembled with care and surface-treated for durability. Matching touch-up paint is provided to maintain both corrosion resistance and visual consistency after installation.
With a strong focus on quality and utility-grade performance, Scotech continues to supply dependable pad-mounted transformers for modern power systems across North America and beyond.
