 Full-Process Solution for 250MVA-220/33kV Transformers in Queensland, Australia

Full-Process Solution for 250MVA-220/33kV Transformers in Queensland, Australia

2026-03-20

I. Project Overview and Technical Specifications
Hengfengyou Electric provides this customized technical solution for the delivery of two 250MVA-220kV power transformers to the Energex Hub Substation in Queensland. As critical assets for the regional grid, these units are designed for long-term stability in tropical climates. They utilize On-Load Tap Changing to manage voltage fluctuations from renewable inputs. The YNyn0+d11 vector group supports industrial loads and renewable energy off-take requirements.
Table: Key Technical Parameters

Parameter	Specification	Remarks
Model	SZ22-250000/220	Three-phase, OLTC, ODAF
Rated Capacity	250MVA	Continuous rating (1.3x overload capable under ODAF)
Voltage Ratio	220±10×1.5% / 33kV	HV side OLTC (AS 60076 compliant)
Vector Group	YNyn0+d11	Adapts to AU earthing & harmonic suppression
Short-Circuit Impedance	Uk=12% (HV-MV) / 14% (HV-LV)	Matches 50kA system fault levels
Cooling Method	ONAN/ONAF/ODAF	Natural/Forced Air/Directed Oil Forced Air
Insulation Level	LI950 AC395 / SI325 AC140	Lightning/Switching Impulse withstand voltage
Environmental	-5°C to +45°C, C5-M Salinity	AS/NZS 60721-3-4 Tropical Coastal Standard

220kV/33kV Power Transformer, Australia 250MVA Transformer Solution, AS/NZS 60076 Standard Design.

II. Design and Development Phase
2.1 Electromagnetic Design
Based on AS/NZS 60076 standards, our team utilizes Ansys Maxwell and JMAG simulation platforms to calculate magnetic flux distribution, leakage fields, short-circuit electrodynamic forces, and hotspot temperature rises. We use Japanese JFE 23ZDKH90 high-permeability grain-oriented silicon steel (loss ≤0.85W/kg @1.7T) with a "three-step annealing process" to minimize magnetostriction noise.
2.2 Structural Engineering
The design phase (28 days) produces comprehensive blueprints for:
Core Structure: 45° full-oblique joints with 7-step lapping. Q355ND low-alloy high-strength steel clamps are validated via ANSYS Workbench for short-circuit resistance (dynamic stress ≤215MPa).
Winding Insulation: HV windings use 0.08mm x 3-layer Nomex paper. LV windings utilize 2.0mm epoxy glass cloth boards for end insulation.
Tank Design: Bell-type structure (16mm wall thickness) with two 300mm explosion-proof valves. Validated via 1.2x design pressure sealing tests (24-hour hold).
Component Selection: German MR VACUTAP® OLTC with online oil filtration; Italian P&V 220kV OIP bushings (creepage 31mm/kV); Swiss SIBA SGA-220 gas relays with digital flow monitoring.
III. Manufacturing and Production
Material Inspection: Dual-source verification for all raw materials. Shell Diala S4 ZX-I inhibited electrical oil is used (breakdown voltage ≥70kV, moisture ≤10ppm).
Core Fabrication: Processed on German GEORG slitting lines (accuracy ±0.05mm). Stacking utilizes vacuum adsorption and laser positioning.
Winding: Performed in a Class 1000 dust-free, climate-controlled workshop. Real-time monitoring of turns (error ≤±0.1) and radial compression (≥8%).
Surface Treatment: Sa2.5 grit blasting followed by a high-spec C5-M coating system: Epoxy zinc-rich primer (80μm) + Epoxy micaceous iron oxide intermediate (120μm) + Acrylic polyurethane topcoat (80μm). Total DFT ≥280μm.
Vapor Phase Drying (VPD): A three-stage kerosene VPD process ensures insulation moisture content ≤0.3% and core moisture ≤0.1%.
IV. Factory Acceptance Testing (FAT)
All tests are witnessed by SAI Global (Australia).
Routine Tests: DC resistance, voltage ratio, vector group verification, and loss measurements (No-load loss 117.8kW vs. 120kW guarantee).
Type Tests: Temperature rise (ODAF: Winding <65K, Top oil <55K); Lightning Impulse (LI 950kV/LIC 850kV).
Special Tests: Short-circuit withstand capability (simulated 50kA/3s); Zero-sequence impedance measurement; Audible noise (73dB at 1m).
V. Logistics and Preservation
Disassembly: Bushings, radiators, and conservators are wrapped in Vapor Phase Inhibitor (VPI) paper.
Nitrogen Padding: The main tank is filled with dry nitrogen (0.02-0.04MPa) and fitted with 304 stainless steel blind plates for transit.
Monitoring: Three-dimensional impact recorders (±0.1g accuracy) and GPS tracking are installed to upload real-time status to the cloud.
Route: Qingdao, China → Brisbane, Australia (28 days sea freight) → Substation site (150km heavy-haul road transport).
220kV/33kV Power Transformer, Australia 250MVA Transformer Solution, AS/NZS 60076 Standard Design.

VI. Onsite Installation and Commissioning (SAT)
Arrival Inspection: Verification of nitrogen pressure and impact recorder data (Max impact ≤32g, well within the 50g threshold).
Vacuum Filling: 24-hour vacuum hold (≤13Pa) followed by hot oil circulation and 48-hour static degassing.
Site Acceptance Testing: Compliance with AS/NZS 60076-3. Includes Frequency Response Analysis (FRA) for winding deformation and partial discharge (PD) measurements (≤100pC).
Energization: Five consecutive no-load soak tests followed by a 48-hour soak and gradual load ramp-up.
VII. Quality Control and Deliverables
7.1 Key Control Points

Stage	Control Point	Standard	Verification
Design	Electromagnetic Review	AS/NZS 60076-1	Tri-party Sign-off
Material	Silicon Steel Testing	IEC 60404-8-4	SQA Lab Report
FAT	Witness Testing	AS/NZS 60076-2	SAI Global Certificate
Logistics	Impact Analysis	ISO 1496-1	Cloud Monitoring

7.2 Documentation Package
Bilingual Test Reports (FAT/SAT).
Operation & Maintenance Manuals (with Australian local support contacts).
Full CAD drawings (DWG/PDF).
Component OEM Certificates (MR, P&V, etc.).
Warranty: 5 years for the unit; 10 years for core components.
VIII. Conclusion
The 250MVA-220kV transformer solution by Hengfengyou Electric bridges high-efficiency "Made in China" manufacturing with the rigorous "Australian Standards." Through localized engineering (C5-M corrosion resistance), stringent quality oversight, and dedicated cross-border support, we ensure long-term grid reliability for Queensland’s challenging tropical environment.

Send a message to the supplier

上一篇：Hengfengyou Electrical Data Center Transformers: Providing Reliable Power Protection for Digital Infrastructure

下一篇：Full-Process Solution for 2000kVA-34.5kV-2.4kV Pad-Mounted Transformer in the Philippines