Oil-immersed distribution transformer: oil-cooled, rock-steady – safeguarding every watt, every day.
01 General
1.1 Project Description
500 kVA IEC 60076 distribution transformer was delivered to Australia in 2025. The rated power of the IEC 60076 distribution transformer is 500 kVA with KNAN cooling. The high voltage is 22 kV with ±2*2.5% tapping range (NLTC), the low voltage is 0.415 kV, they formed a vector group of YNyn0.
This 500kVA, three-phase, hermetically sealed distribution transformer is designed for harsh outdoor environments, it complies with IEC 60076 and AS/NZS standards, offering high efficiency (≥99.16%) and reliable operation under extreme conditions (up to 50°C ambient).
Key Technical Highlights
- FR3 Fluid: Biodegradable, high-fire-point (≥300°C) natural ester, enhancing fire safety and insulation life.
- HV Cable Box: IP56-rated, fully enclosed, with bottom entry and elbow plug-in terminations for safe, weatherproof connections.
- LV Cable Box with Extended Copper Busbars: IP56-rated enclosure including extended copper busbars and supports for easy, flexible LV cable termination.
- Terminal Box with Anti-Condensation Heater: IP56 terminal box fitted with a 230V AC space heater to prevent moisture buildup and ensure long-term control circuit integrity.
- Secondary (Control) Contacts: Provides WTI (110°C alarm / 130°C trip), oil temperature, pressure relief, and low oil level alarms – all with 230V AC contacts for SCADA integration.
This transformer combines robust sealing, eco-friendly FR3 fluid, and comprehensive IP56 protection, delivering safe and dependable power distribution in demanding environments.
1.2 Technical Specification
500 kVA IEC 60076 distribution transformer specifications type and data sheet
| Delivered to | USA |
| Year | 2025 |
| Type | Pad mounted transformer |
| Standard | IEC60076 |
| Rated Power | 500 kVA |
| Frequency | 50HZ |
| Phase | 3 |
| Cooling Type | KNAN |
| Primary Voltage | 22 kV |
| Secondary Voltage | 0.415 kV |
| Winding Material | Copper |
| Vector Group | YNyn0 |
| Impedance | 5.75%±7.5% |
| Efficiency | ≥99.16% |
| Tap Changer | NLTC |
| Tapping Range | ±2*2.5% |
| No Load Loss | ≤0.95 kW |
| On Load Loss | ≤5.8 kW |
1.3 Drawings
500 kVA IEC 60076 distribution transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The transformer core is made of cold-rolled grain-oriented silicon steel with a stepped lap structure. The magnetic circuit design is advanced and fully meets the project requirements for low losses and high permeability. The design and manufacturing comply with IEC 60076. Measured no‑load loss is only 0.785 kW (requirement ≤0.95 kW), and no‑load current is 0.68% (requirement ≤1.2%). Both key indicators are better than typical limits, proving excellent core loss control. For quality assurance, core stacking uses high‑precision equipment, each joint is strictly controlled, and in‑process magnetic performance is sampled. Manufacturing highlights: stepped lap joints, low‑loss silicon steel, full‑process magnetic performance monitoring. |  |
2.2 Winding
 | The winding uses electrolytic copper with purity ≥99.9% and precision winding processes, fully meeting the project’s conductivity and thermal requirements, and complying with IEC 60076 standards for resistance and temperature rise. Measured HV winding temperature rise is 58.69 K (requirement ≤60 K), LV winding temperature rise is 57.84 K (requirement ≤60 K), and the maximum resistance unbalance is only 0.41%. These figures demonstrate uniform winding structure and excellent heat dissipation. Quality assurance includes automatic winding machines with real‑time resistance monitoring and multi‑layer insulation. Manufacturing highlights: high‑purity copper conductors, automatic winding + real‑time resistance monitoring, multi‑layer insulation for longer life. |
2.3 Tank
The tank is a fully sealed corrugated steel structure with IP56 protection, no conservator and no nitrogen cushion, fully suitable for harsh outdoor environments, and designed according to IEC 60076 sealing and protection standards. The leak test at 15 kPa for 24 hours showed no leakage, and the applied voltage test (HV side 50 kV / 60 s) passed without issue, confirming reliable sealing and voltage withstand capability. Quality assurance: 100% inspection of all welds, complete pressure sealing test. Manufacturing highlights: fully sealed corrugated design, IP56 high protection grade, RAL7035 corrosion‑resistant coating. |  |
2.4 Final Assembly
 | The final assembly integrates several key features: FR3 natural ester oil (high fire point, biodegradable, environmentally friendly and safe); HV side with enclosed IP56 HV cable box, bottom entry, elbow plug‑in connectors; LV side with LV cable box plus extended copper bars and supports for easy field wiring; terminal box with built‑in anti‑condensation space heater (230V / 50W) to prevent moisture; complete secondary wiring contacts including winding temperature indicator, oil temperature indicator, pressure relief valve, low oil level alarm, etc. All components are designed according to IEC 60076 accessory standards. Reliability testing: induced voltage withstand test at 30.8 kV / 150 Hz for 40 seconds – no breakdown; lightning impulse test at 125 kV full wave – passed. This proves complete insulation system integrity and reliable accessory function. Quality assurance: 100% functional testing of all accessories before assembly, one‑to‑one verification of wiring diagrams against actual hardware, full simulation run before dispatch. Manufacturing highlights: integrated HV/LV cable boxes, anti‑condensation heated terminal box, pre‑installed full‑function secondary wiring contacts. |
03 Testing
The transformer has undergone complete routine and type tests, strictly following IEC 60076‑1/2/3/10, with all items passed and many indicators better than typical requirements. Key test results: no‑load loss 0.785 kW (better than ≤0.95 kW), load loss 5.764 kW (better than ≤5.8 kW), short‑circuit impedance 5.90% (within tolerance), HV winding temperature rise 58.69 K, top oil temperature rise 49.53 K (better than ≤60 K and ≤55 K respectively), leak test 24h – no leakage, lightning full‑wave impulse 125 kV – passed, applied voltage 50 kV / 60 s – passed, sound pressure level only 47.3 dB(A) (far better than ≤75 dB(A)). Quality assurance: all test equipment regularly calibrated, certified test personnel, three‑level review of test reports. Manufacturing highlights: full‑process test coverage, traceable data, compliance with international standards.
04 Packing and Shipping
4.1 Packing
The transformer is packed in a high‑strength shockproof wooden case or steel frame. External dimensions are controlled within 2000×1400×1800 mm, total weight not exceeding 3200 kg, meeting space and load requirements for various containers and bulk transport. The packing design complies with international export standards (e.g., ISPM 15 heat treatment requirements). Before packing, the entire unit is moisture‑treated. The transformer is secured inside the case with multi‑point fastening and cushioning materials to prevent transport vibration damage. An optional shock indicator can be installed to monitor impacts during transit. Quality assurance: final visual and functional check before packing, full supervision and photo documentation of the loading process. Manufacturing highlights: high‑strength export‑grade packing materials, combined moisture and shock protection, optional shock indicator. |  |
4.2 Shipping
 | Shipping is by sea to Fremantle Port, Australia, under CIF terms, with a committed delivery date of March 15, 2026. An optional built‑in transport monitoring system can record real‑time temperature, humidity, shock, and location data, ensuring full traceability. The shipping process complies with IEC 60076 requirements for transport conditions. Before dispatch, the transformer has completed all tests and all movable parts are locked. Reliability: transport vibration analysis is used to optimise the fixing scheme, and a trial loading verification is performed before actual shipment. Quality assurance includes selecting a logistics provider experienced in power equipment transport, a final sign‑off by a quality inspector before dispatch, and provision of transport insurance. Manufacturing highlights: optional real‑time transport monitoring system, fully traceable logistics, strict adherence to delivery date. |
05 Site And Summary
In summary, this 500 kVA / 22 kV / 0.415 kV oil‑immersed distribution transformer performs excellently in core, winding, tank, final assembly, testing, packing and shipping. Measured data show no‑load loss 0.785 kW, load loss 5.764 kW, HV winding temperature rise 58.69 K, top oil temperature rise 49.53 K, short‑circuit impedance 5.90%, leak test 24h no leakage, lightning impulse 125 kV passed, applied voltage 50 kV passed, sound pressure level only 47.3 dB(A) – all indicators passed and many far better than typical requirements. Manufacturing processes with strict quality control and full‑process testing ensure product consistency and reliability. Key highlights include: low‑loss stepped‑lap core, high‑purity copper windings, fully sealed IP56 corrugated tank, FR3 environmentally friendly high‑fire‑point oil, HV cable box, LV cable box with extended copper bars, anti‑condensation terminal box, and complete secondary wiring contacts. This transformer is fully suitable for harsh outdoor environments, meeting the demands for high efficiency, low maintenance, and high safety.
