Reliable and efficient power for Canadian distribution networks with our 500 kVA pad-mounted electrical transformers, built for durability and dual high-voltage operation
01 General
1.1 Project Description
In 2024, a Canadian client received a 500 kVA electric transformer box, designed and manufactured in accordance with CSA Standard C227.4:21. The unit is intended for outdoor pad-mounting on concrete foundations and is suitable for use in loop-fed, effectively grounded distribution systems.
This electric transformer box features a dead-front design for safety and easy operation. It uses ONAN cooling with mineral oil insulation, and aluminum windings for a good balance of efficiency, weight, and cost. The transformer is rated 500 kVA, 60 Hz, with dual high-voltage ratings of 12.47/4.16 kV and a secondary voltage of 0.208 kV, configured as YNyn0.
A key design feature of this unit is its five-legged core construction, which provides superior magnetic stability, reduces losses, and enhances performance under GrdY–GrdY or dual high-voltage connection schemes. The transformer has a no-load tap changer (NLTC). It gives a ±2×2.5% tapping range. This allows the voltage to be adjusted easily under different load conditions.
The unit reaches 99.05% efficiency. The no-load loss is ≤1090 W. The load loss is ≤5800 W. It is built for outdoor use and is very durable. The electric transformer box comes with standard CSA-compliant accessories. It is a reliable solution for Canadian distribution networks and supports dual high-voltage connections.
1.2 Technical Specification
500kVA three phase pad mounted transformer specification and data sheet
| Delivered to | Canada |
| Year | 2024 |
| Type | Three phase pad mount transformer |
| Standard | CSA C227.4:21 |
| Rated Power | 500KVA |
| Frequency | 60HZ |
| Feed | Loop |
| Front | Dead |
| Phase | three |
| Number of core leg | 5 |
| Cooling Type | ONAN |
| Liquid insulant | Mineral Oil |
| Primary Voltage | 12.47(4.16) kV |
| Secondary Voltage | 0.208 kV |
| Vector Group | YNyn0 |
| Winding Material | Aluminum |
| Impedance | 5% |
| Efficiency | 99.05% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | ≤1090 W |
| On Load Loss | ≤5800 W |
| Accessories | Standard Configuration |
1.3 Drawings
500kVA electric transformer box drawing and nameplate
02 Manufacturing
2.1 Core
The silicon steel has high magnetic ability and a narrow hysteresis loop. This makes magnetizing easier and lowers heat inside the core. The balanced five-limb shape also helps reduce no-load losses. The transformer operates efficiently and remains cool under normal use.
2.2 Winding
 | All coils are carefully wound by skilled workers using aluminum foil and wire, ensuring precise construction and effective cooling to reduce losses. The experience of the winders guarantees uniform winding, strong mechanical strength, and reliable insulation. With optimized impedance and high efficiency, each transformer delivers consistent performance and is ready for pad-mounted installation. |
2.3 Tank
| Each unit shall incorporate a sealed mild-steel tank with bolted cover, capable of withstanding 50 kPa gauge pressure without leakage or distortion beyond 0.25 % of the diagonal length. The enclosure shall be protected with anti-corrosion coating and secured using captive pentahead bolts, ensuring tamper-resistant and weather-resistant construction as per CSA C227.4. |  |
2.4 Final assembly
By implementing standardized operating instructions covering the entire process, we ensure the accuracy and traceability of assembly operations. Furthermore, final assembly is conducted in a cleanroom with constant temperature and humidity. Quality inspectors conduct full-process inspections and conduct specialized inspections of key processes, ensuring lean control of the production environment and process quality. This deep integration of standardization and lean processes is key to our products’ ability to consistently meet high standards.
03 Testing
Testing Standard and Routine Test
| CSA C227.4-21 | Three-phase, pad-mounted distribution transformers with separable insulated high-voltage connectors |
| CSA-C802.1-13 (R2022) | Minimum Efficiency Values for Liquid-Filled Distribution Transformers |
1. Resistance Measurements
2. Ratio Tests
3. Phase Relation Test
4. No Load Losses and No Load Current
5. Load Losses Impedance Voltage and Efficiency
6. Applied Voltage Test
7. Induced Voltage Withstand Test
8. Leak Testing with Pressure for Liquid Immersed Transformers
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 | 4.57 | Pass |
| 2 | Ratio Tests | % | The deviation of voltage ratio on the principal tapping: ≤0.5% | -0.04-0.10 | Pass |
| 3 | phase-relation tests | / | YNyn0 | YNyn0 | Pass |
| 4 | No-load losses and excitation current | / | I0 :: provide measured value | 0.48% | Pass |
| P0: provide measured value | 0.8246kW | ||||
| 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 | 5.36% | ||||
| Pk: measured value | 4.889kW | ||||
| Pt: measured value | 5.750kW | ||||
| Efficiency not less than 99.05% | 99.22% | ||||
| 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): 2 Ur | No collapse of the test voltage occurs | Pass |
| Duration(s):30 | |||||
| Frequency (HZ): 240 | |||||
| 8 | Leakage Test | kPa | Applied pressure：20kPA Duration：12h | No leakage and no Damage | Pass
|
| 9 | Insulation Resistance Measurement | GΩ | LV-HV to Ground | 9.7 | / |
| HV&LV to Ground | 12.2 | ||||
| 10 | Oil Test | / | Dielectric Strength | 53.5 kv | Pass |
| Moisture Content | 10.5 mg/kg | ||||
| Dissipation Factor | 0.00332% | ||||
| Furan Analysis | ≤0.1 | ||||
| Gas Chromatography Analysis | / |
04 Packing and Shipping
05 Site And Summary
Our 500 kVA three-phase pad-mounted transformer gives reliable and efficient power for Canadian distribution networks. It meets CSA C227.4:21 standards. The electric transformer box has a strong five-limb silicon steel core. Aluminum windings are precisely made for good cooling and low losses. The tank is weatherproof and tamper-resistant. Skilled workers assemble each unit carefully. Standardized processes and full quality checks ensure long-lasting performance.
