WEG has manufactured and supplied two large scale transformers to the biggest operational hydroelectric plant in the world, the Itaipu Binacional, which is a bi-national undertaking by Brazil and Paraguay. The hydro-electric plant straddles the Parana’ river, as it crosses the border between the two South American countries. To-date, two power transformers, each weighing 200- tons, have been supplied by WEG: a TR 256 MVA/550kV, 60Hz on the Brazilian side, and a TR 275 MVA/550kV, 50Hz unit in Paraguay.

WEG’s achievement in securing this project is a double celebration for the company: in the manufacture of the equipment WEG became the first company in the world to carry out VFT - Very Fast Transient tests - on transformers. This testing is essential to assure that the transformers will cope with very fast voltage oscillations during their operation. It has never before been carried out at the final testing stage, due to its complexity, risk and high cost.

Manufactured at WEG’s transformer plant in Blumenau, in the state of Santa Catarina, the two power transformers will start operation at Itaipu at the beginning of 2010 in a gas insulated substation (GIS).

“We have met all of the customer’s requirements using the most modern technology in the world on the design, in the manufacturing, and in the testing of these transformers to very fast transients,” said Francisco Rebordão, technical manager at WEG Transformadores. “As a result, we are sure that we have supplied an efficient and highly safe product.”

WEG was appointed to supply the equipment to Itaipu in 2003, and since then has made substantial investments in its infrastructure and technology to meet the needs of the energy sector. During the past three years the company has injected more that US$30-million into the Blumenau plant. US$4-million, alone, was invested on the expansion of the laboratory facilities at the plant. “To supply equipment of this size, to the largest hydroelectric power plant in the world, proves we are ready to meet the needs of both the domestic and foreign markets,” said Carlos Diether Prinz, Director at WEG Transformadores.

WEG and Itaipu are also partners in other innovative projects such as the Palio Elétrico, developed along with Fiat.

VFT Testing
WEG tested its transformers to simulate the very fast voltage transients, which are common in gas insulated substations. The VFTsurges were generated by chopping the waves of SF6 gas, using the testing device specially developed by WEG for this purpose. During the tests, the technical team evaluated, among other variables, the occurrence of discharges of any nature, internal or external, and eventual perforations in the insulation. The total combination of tests for both transformers lasted approximately 2- months.

Application
The TR 275 MVA 60 Hz will be installed as replacement equipment on the Brazilian side of the plant and the TR 256 MVA 50 Hz on the Paraguayan side.

Technical data

• 275 MVA 50 Hz:
  Total weight: 228.135 kg
  Length: 6915 mm
  Width: 6440 mm
  Height: 7695 mm
• 256 MVA 60 Hz:
  Total weight: 202.965 kg
  Length: 6650 mm
  Width: 6300 mm
  Height: 7260 mm

Investments
Since 2006, WEG has already invested over R$ 56 million on infra-structure and technology on the Blumenau plant.
To meet the demand of the domestic market, the United States, Canada and Central America, WEG has invested R$30 million on the construction of a new plant of transformers in Mexico, inaugurated in April of this year.
For the Itaipu project, WEG has invested R$8-million on testing equipment and on the construction of a new laboratory to carry out tests on the large size transformers.