Smart Power Where You Need It – Pad-Mounted Transformers for Modern Grids.
01 General
1.1 Project Description
3000 kVA pad mounted transformer was delivered to Canada in 2025. The rated power of the transformer is 3000 kVA with ONAN cooling. The primary voltage is 25GrdY/14.434 kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.6Y/0.347 kV, they formed a vector group of YNyn0.
Our CSA-certified pad-mounted transformers are engineered for safe, reliable, and efficient power distribution in urban, commercial, and industrial applications. Designed to meet CSA C227.4:21 standards, these robust units ensure full compliance with Canadian electrical safety requirements, delivering superior performance in harsh weather conditions and high-load environments.
Featuring compact, tamper-resistant enclosures, advanced cooling systems, and corrosion-resistant materials, our transformers provide long-term durability with minimal maintenance. Whether for underground-to-overhead conversions, renewable energy integration, or utility grid upgrades, our CSA-approved pad-mounted transformers offer trusted power distribution solutions backed by rigorous testing and quality assurance.
1.2 Key Design Highlights
Ring Main Plug-In Structure
This transformer comes with a ring main plug-in setup, which makes switching in the network quick and flexible; maintenance is easier too, safer for operators.
High & Low Voltage Connections
High-voltage and low-voltage interfaces are carefully arranged; compact layout, easy to connect to load switches or other devices. Saves space and keeps things organized.
Front Dead-End Design
Front dead-end design adds an extra layer of safety. Operators can inspect or handle parts without worrying about live high-voltage contact.
BIL & Bushing Arrangement
High-voltage BIL up to 125 kV, low-voltage four-hole spade bushings. Provides solid insulation, reliable performance, and convenient installation-good fit for both urban and industrial networks.
1.3 Technical Specification
3000 kVA pad mounted transformer specifications type and data sheet
| Delivered to | Canada |
| Year | 2025 |
| Type | Pad mounted transformer |
| Standard | CSA C227.4:21 |
| Rated Power | 3000 kVA |
| Frequency | 60HZ |
| Phase | 3 |
| Feed | Loop |
| Front | Dead |
| Cooling Type | ONAN |
| Primary Voltage | 25GrdY/14.434 kV |
| Secondary Voltage | 0.6Y/0.347 kV |
| Winding Material | Aluminum |
| Angular displacement | YNyn0 |
| Impedance | 5.75% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | 3.46 kW |
| On Load Loss | 27 kW |
1.4 Drawings
3000 kVA pad mounted transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| Iron core：The iron core of a pad-mounted transformer typically features a three-phase five-limb stacked core, constructed from high-permeability silicon steel laminations. This design includes three main limbs (for winding the three-phase coils) and two auxiliary side limbs, forming a closed magnetic circuit to minimize no-load loss and flux leakage. The laminated layers reduce eddy current losses, while the five-limb configuration enhances magnetic balance, making it ideal for load-varying applications with high efficiency and low noise operation. |  |
2.2 Winding
 | Winding: The winding of a pad-mounted transformer features a combined design of low-voltage foil winding and high-voltage wire winding. The primary coil on the high-voltage side is wound with insulated copper wire to enhance dielectric strength and cooling efficiency. The low-voltage side employs aluminum or copper foil windings with interlayer insulation, offering compact construction, reduced losses, and high mechanical stability. This hybrid winding configuration improves the transformer’s efficiency and reliability for demanding outdoor applications. |
2.3 Tank
| Tank: The tank of a pad-mounted transformer typically employs bunded oil tanks, constructed from corrosion-resistant steel with an inner oil chamber and an outer containment shell to prevent leaks and environmental contamination. The compact tank features reinforced ribs for pressure resistance and integrated cooling fins for improved heat dissipation. This design complies with environmental regulations while ensuring long-term sealing reliability and safety in outdoor operation. |  |
2.4 Ground Strap Copper
 | Ground Strap Copper：Provides a low-impedance path-so any unexpected leakage, fault current, it goes straight into the earth, keeps people and equipment safe. Also helps with electrical interference, overvoltages that pop up when grounding isn’t perfect. Copper, strong and corrosion resistant, very good conductor; lasts long, reliable over time, easy to trust in operation. CSA Ground Bracket：Standardized mounting point for connecting ground wires or straps; ensures grounding meets CSA safety standards, certification requirements. Bracket design-sturdy, withstands mechanical stress, vibration, wind, corrosion; provides a durable, reliable grounding solution, easy to install and inspect. |
03 Testing
| No. | Test Item | Unit | Acceptance Values | Measured Values | Conclusion |
| 1 | Resistance Measurements | % | Maximum resistance unbalance rate | 2.75 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ±0.5% | 0.09 | Pass |
| 3 | phase-relation tests | / | YNyn0 | YNyn0 | Pass |
| 4 | No-load losses and excitation current | / | I0 :: provide measured value | 0.25% | Pass |
| P0: provide measured value | 3.0807kW | ||||
| 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 | 5.71% | ||||
| Pk: measured value | 26.305kW | ||||
| Pt: measured value | 29.3857kW | ||||
| Efficiency not less than 99.37% | 99.40% | ||||
| 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):2Ur | No collapse of the test voltage occurs | Pass |
| Duration(s):30 | |||||
| Frequency (HZ): 240 | |||||
| 8 | Leakage Test | kPa | Applied pressure：50kPA Duration：12h | No leakage and no Damage | Pass |
| 9 | Insulation Resistance Measurement | GΩ | LV-HV to Ground | 10.3 | / |
| 10 | Oil Test | / | Dielectric Strength; | 56.3 kv | Pass |
| Moisture Content | 8.5 mg/kg | ||||
| Dissipation Factor | 0.198% | ||||
| Furan Analysis | ≤0.1 mg/kg | ||||
| Gas Chromatography Analysis | / |
04 Packing and Shipping
4.1 Packing
| 1. Place the 3 phase transformer on the tray, cover it with a tin foil bag, initially seal the bag with an opening left, vacuumize through the opening, and then seal the opening. Put desiccant inside to prevent rusting. 2. Add corner protectors (foam/plastic/cardboard) around the transformer and wrap it with protective film. 3. Package it in a wooden box and spray forklift and center of gravity markings on the box. |  |
4.2 Shipping
 | The pad-mounted transformer is packed in a wooden crate and loaded onto a truck using a forklift, then transported to container port. It is shipped under CIF (Cost, Insurance, and Freight) terms via sea freight to the destination port of Montreal, Canada. The entire process ensures moisture-proofing, shock resistance, and secure fastening in compliance with international shipping standards. |
05 Performance Advantages
High Efficiency & Low Losses
Efficiency hits 99.37%, while no-load and load losses stay low-saves energy, reduces running costs.
Durable Aluminum Windings
Aluminum windings, standardized and long-lasting; light, robust, minimal maintenance. Designed for heavy-duty operation, yet predictable in daily use.
Overload Capacity & Reliability
Handles overloads well. Even under sudden high load, it stays stable. High reliability, minimizes downtime.
Balanced Operation in Three-Phase Systems
Keeps all three phases balanced. Smooth operation, less risk of faults. Overall, energy-efficient, safe, and easy to operate-operators can rely on it day after day.
