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HVDC transformers are key components of HVDC stations. HVDC converter and inverter stations terminate long-distance DC transmission lines or DC sea cables. This type of transformer provides the interface between AC grids and high power rectifiers and are used to control the load flow over the DC transmission lines. These actors adapt the AC grid voltage to an adequate level which is suitable for feeding the valve system of DC converter and inverter.
Design options
The design concept of HVDC transformers is mainly influenced by the rated voltage, rated power and transportation requirements like dimensions, weight and mode of transportation.
Many large power HVDC converter station are located in rural areas of low infrastructure. Frequently, special geometrical profiles have to be fulfilled in order to move such transformers by railway.
Typically, HVDC transformers are single phase units containing 2 winding limbs. This concept can include either 2 parallel valve windings (two for delta or two for wye system, fig. 5.8-1) or two different valve windings. In order to reduce the total transportation height frequently the core assembly includes 2 return limbs. Due to redundancy requirements in HVDC stations 3 phase units are quite uncommon.
The valve windings are exposed to AC and DC dielectric stress and therefore a special insulation assembly is necessary. Furthermore, special lead systems connecting the turrets and windings have to be installed in order to withstand the DC voltage of rectifier. Additionally, the load current contains harmonic components of considerable energy resulting in highe r losses and increased noise. Above all, special bushings are necessary for the valve side to access upper and lower winding terminals of each system from outside. Conclusively, two identical bushings are installed for star or delta system.
For approving the proper design and quality of manufacturing special applied DC and DC polarity reversal tests have to be carried out. The test bay has to be equipped with DC test apparatus accordingly and needs to provide adequate geometry to withstand the DC test voltage.

HVDC Transformers react as coupling elements between the connected AC grids and high power rectifiers, and are necessary for adapting the voltage. They insulate the rectifier itself from the AC grid and generate a phase shift.
New HVDC applications are seen between existing, well-established networks. A back-to-back link can easily combine two different AC networks together, even with different frequencies.
Such solutions can also help customers to strengthen and optimize their networks. The changing environment provides more and more opportunities to HVDC solutions, and Siemens is prepared to provide its customers with either our solution or with converter transformers as a loose component



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Electrical laminated wood is mainly used for transformers; it is also the insulation material and support material of mutual inductor. Besides, it can be used to make winding clamping plate, iron core plate, trapezoidal plate and clamping device. And it has many advantages, such as proper specific weight, high mechanical strength, good compatibility with transformer oil and easy machining. In addition, its dielectric constant is close to that of transformer oil and the insulation coordination between them is proper. It can be used in transformer oil under 105â?? for a long time.

Electrical laminated wood sheet is widely used in manufacturing some devices for oil-filled transformer, such as upper and lower pressure plate, lead bracket and iron yoke cushion block. And it is used to make clamping device in mutual inductor. It can replace steel plate, insulation paper board, epoxy paper board and epoxy fiberglass board, which can lower the weight of the transformer and the cost of materials.

It has been recognized to GB/T20634 or IEC61061.

Product Description
Type: Dry Type Transformer

Model Number: SC(B)10-30~2500/35

Phase: Three

Rated High Voltage: 10(11, 10.5, 6.6, 6.3, 6 )KV

Rated Low Voltage: 10KV, 0.4KV or as required

Rated Capacity: 30~2500KVA
Our dry type transformers are in conformity with the following standards:

1. National Standard of China GB1904.11-2007Power Transformers
2. International Electro Technical Commission Standards IEC 60076-112004 Dry Type Transformers
3. German Industry Standard DIN EN 60076-11:2005 Dry Type Transformers