Ruibian (Jiangsu) Electric Power Co., Ltd. is one of the leading manufacturers and suppliers of 330kv 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.
Special Materials & Exclusive Technologies
Special conductor specifications
Self-bonding transposed conductors (CTC) or composite insulated transposed conductors are adopted, cutting circulating current losses by 30% to 50% and boosting mechanical strength significantly.
Insulation pressboard
Premium imported wood pulp insulation pressboards from brands like Weidmann and Temec are applied, with density above 1.2g/cm³ and breakdown strength no less than 70kV/mm.
Lead-out assembly
The 330kV lead-out assembly adopts a composite structure of capacitive bushing and grading sphere. Finite element simulation is used to optimize electric field distribution, limiting the maximum electric field strength below 10kV/mm.
Reinforced tank structure
Bell-type oil tanks are fabricated with steel plates ranging from 12mm to 16mm thick, fitted with internal stiffeners and positioning stays. The tank can withstand vacuum pressure down to 133Pa and internal pressure above 0.1MPa.
Core Advantages
1. Superior high-altitude adaptability: Customized for Northwest plateaus at altitudes between 1000m and 3000m. External insulation creepage distance is reinforced in line with Class II or III pollution grades, enabling stable operation under low air pressure and intense ultraviolet radiation.
2. High-capacity heat dissipation: Equipped with ODAF (Forced Oil Directed Air Forced) or OFAF (Forced Oil Air Forced) cooling modes, the heat dissipation capacity can reach several thousand kilowatts to guarantee full-load operation under high ambient temperatures.
3. Low-noise construction: Integrated noise reduction solutions including stepped core lap joints, elastic suspension of the active part and damped steel plate composite tank structure keep the sound power level below 65dB(A), complying with environmental protection standards.
4. Extended service life design: High-temperature insulating materials such as NOMEX and DMD are used for insulation components, delivering a thermal service life of over 30 years in accordance with IEEE C57.91 standards.
5. Grid-friendly performance: Short-circuit impedance can be customized from 10% to 18%. The transformer supports reactive power compensation access on the low-voltage side and accommodates high penetration of new energy power sources.
Application Scenarios
- Northwest Power Grid: Hub substations and switching stations on the 330kV main power grid
- Large hydropower plants: Step-up transformers for cascade hydropower stations along the upper Yellow River
- New energy bases: Collector transformers for large wind-solar-storage integrated bases in Qinghai and Gansu
- Inter-regional grid interconnection: Tie transformers linking Northwest Grid with North China and Central China power grids
Packaging & Transportation
Railway transportation
330kV transformers are generally shipped via special D2 or D3 railway flatcars. Transport plans must be submitted in advance and approved by railway authorities.
Highway transportation
If road delivery is adopted, 12-axis or 16-axis hydraulic flatbed trucks are required, and load-bearing checks shall be carried out for all bridges along the transport route.
Customs clearance for export
330kV transformers exported to Central Asian countries such as Kazakhstan and Kyrgyzstan are designed for broad-gauge railway transport with a track gauge of 1520mm.
FAQ
Q1: Why are single-phase units more widely adopted for 330kV transformers instead of three-phase integrated structures?
A: For ultra-large capacities such as 240MVA and 360MVA, three-phase integrated transformers exceed the limits of transportation dimensions and weight. A bank of three single-phase transformers eliminates transport obstacles and improves power supply reliability - a single-phase fault only cuts off one-third of the total capacity.
Q2: What impacts do high altitudes exert on the external insulation of transformers?
A: For every 1000-meter rise in altitude, air density drops by roughly 10%, and the flashover voltage of external insulation decreases by 10% to 12%. Therefore, transformers deployed at high altitudes require extended creepage distance or silicone rubber composite bushings.
Q3: How is the water circulation system configured for ODAF cooling?
A: A closed circulation loop is commonly adopted. Cooling water exchanges heat with hot transformer oil through stainless steel shell-and-tube heat exchangers, with the outlet temperature of cooling water controlled below 40℃. The water circulation system is fitted with two water pumps, one in operation and the other on standby.
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