Ruibian (Jiangsu) Electric Power Co., Ltd. is one of the leading manufacturers and suppliers of 500kv ultra-high voltage series oil-immersed power transformers in China. With abundant experience, our factory offer high quality products made in China with competitive price. Welcome to contact us for pricelist.
Premium Materials & Top-Tier Manufacturing Processes
Ultra-optimized iron core
Ultra-thin laser-scribed silicon steel sheets of 0.23mm or even 0.20mm thickness are used. Combined with step multi-step lap joints and plasma surface treatment for the core, core loss is cut below 0.7W/kg.
Ultra-reliable insulation system
The main insulation adopts a composite structure of extra-thick insulation pressboards (thickness ≥8mm) and precision oil gaps. Its power frequency withstand voltage reaches no less than 630kV for 1 minute, and lightning impulse withstand voltage hits a peak value of 1675kV.
Ultra-precise lead-out assembly
Imported capacitive lead-out assemblies from brands including Weidmann and Hitachi Energy are applied. Multi-layer capacitive screens equalize voltage distribution, limiting the maximum operating electric field strength to 8kV/mm or lower.
Ultra-robust oil tank
Constructed with high-strength steel plates of 16mm to 20mm thickness. It can endure vacuum pressure down to 133Pa and internal pressure above 0.15MPa. Finite element analysis is conducted to guarantee safety during transportation and long-term operation.
Core Advantages
1. Ultra-large capacity: The three-phase capacity of a single unit ranges from 500MVA to 1000MVA, and single-phase capacity can reach 400MVA, meeting power transmission demands of gigawatt-level power bases.
2. Extremely low energy loss: Designed to meet top-tier efficiency standards S22 and S23. With a 3D magnetic circuit structure and optimized winding layout, the total loss is reduced by 40 to 50 percent against the GB/T 6451 standard.
3. Extremely low partial discharge: Partial discharge magnitude is controlled below 30pC with the support of an ultra-clean assembly workshop (ISO Class 6 cleanliness), precise vacuum oil filling and strict defect control throughout production. The insulation service life is greatly prolonged.
4. Comprehensive intelligent monitoring: Equipped with a full set of smart transformer monitoring systems, covering dissolved gas analysis, fiber optic temperature measurement, partial discharge detection, mechanical characteristic monitoring for on-load tap changers, bushing insulation monitoring and vibration monitoring.
5. Eco-friendly alternative solutions: Natural ester insulating oil such as FR3 and Midel 7131 is available as an optional upgrade. It features biodegradability and extremely low fire hazards, making it ideal for sites with stringent environmental protection requirements.
Application Scenarios
- Cross-regional grid interconnection: Hub substations on the 500kV/550kV main power grid
- Super-large power plants: Step-up transformers for 1000MW thermal power units and large nuclear power bases
- Offshore wind power: Interconnection transformers for voltage source converter high voltage direct current (VSC-HVDC) transmission systems
- UHV supporting projects: Step-down transformers and tie transformers for certain UHV substations
Packaging & Transportation
Marine transportation as the primary delivery method
Most 550kV transformers are shipped by sea to project sites such as coastal nuclear power stations and offshore wind platforms. The oil tank undergoes heavy anti-corrosion treatment compliant with C5M corrosion grade.
On-site final assembly
Due to oversized dimensions and weight, transformers are delivered as semi-finished products. Final procedures including active part installation, lead connection and vacuum oil filling are completed in a clean assembly room upon arrival.
Imported spare components
Bushings, on-load tap changers, cooling equipment and other key parts may be imported. Relevant import permits and commodity inspection formalities need to be processed in advance.
FAQ
Q1: Why are autotransformers widely adopted for 500kV/550kV applications?
A: Compared with two-winding transformers, autotransformers feature smaller footprint, lighter weight, lower power loss and lower overall investment. They are particularly suitable for large-capacity scenarios with a relatively small transformation ratio such as 550/242kV.
Q2: What are the differences between natural ester insulating oil and mineral transformer oil?
A: Natural ester oil boasts a fire point of over 300°C, while mineral oil only reaches 160°C. It is biodegradable and has strong water absorption capacity to slow down aging of insulation paper. However, it comes with a higher price tag, and compatibility with all sealing materials must be verified before use.
Q3: Why is reliable earthing of the bushing tap end critical?
A: Poor earthing of the capacitive bushing tap end will trigger suspended potential discharge, which may eventually lead to bushing explosion. Regular inspections on tap end earthing connections are required during operation to maintain stable and reliable grounding.
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