More reliable Power Transformers up to 670 MVA thanks to high thermal class CTC and PWC

calendar_today Monday 08 January 2024

We celebrate a success of innovation and reliability in the supply of transformers for Tamini made with innovative CTC conductors and taped wires, insulated with Nomex T910

De Angeli Prodotti has established itself as a leader in the production of semi-finished products for power transformers, providing advanced and reliable solutions for the ever-growing needs of the energy market. Among the leading products, the Continuously Transposed Cables (CTC) and the Paper Wrapped Conductors (PWC) stand out, characterized by cutting-edge insulation systems developed in collaboration with Du Pont, using the innovative Nomex T910 material.

Proprietary Nomex T910 insulation, a hybrid combination of cellulose and Nomex, has proven crucial in raising the thermal class of the insulation, helping to improve the life, reliability and temperature peak resistance of power transformers .

An emblematic example of the application of this innovative technology is represented by the supply of semi-finished products for the construction of two high-power transformers by Tamini in 2022.

Trasformatore Tamini dupont Nomex t910
One of the transformers made by Tamini with Nomex T910 taped conductors

What are the characteristics of DuPont™ Nomex® T910?

DuPont™ Nomex® 910 is a unique insulating material composed of high electrical grade cellulose pulp. The product is composed of both cellulose and Nomex® aramid.

Nomex® 910 Engineered Cellulose Paper
Nomex® 910 Engineered Cellulose Paper

Nomex® 910 was developed as an interlayer insulation for various applications such as liquid-immersed distribution transformers and small transformers but can also be used for wire winding (conductor insulation) in any transformer, including large power transformers.

Nomex® 910 has better physical and electrical characteristics than existing papers composed of cellulose only. Based on aging data, it also provides a longer life under standard thermal conditions. Nomex® 910 can be compared to TUK (Thermally Upgraded Kraft) insulation as it is more thermally stable than standard kraft insulation.

Thermal aging

Long-term thermal aging tests in sealed tubes were conducted using procedures outlined in the IEEE
Standard for Thermal Aging (IEEE C57.100™ – 2011).

  • Based on long-term testing in mineral oil: Nomex® 910 – Thermal Class 130
  • Based on long-term testing in ester liquid: Nomex® 910 – Thermal Class 140

Tamini’s Power Transformers: two applications of 670 MVA and 340 MVA

An example of the use of this particular insulation system is the application for the construction of two important 670 MVA and 340 MVA transformers of Tamini in 2022, with the following characteristics:

670 MVA Power Transformer

  • Type: Three-phase – Generator step-up
  • Rated power: 670 MVA
  • Cooling: ODAF
  • Voltage ratio: 400000 ± 8 x 1.25% / 22 kV (with on load tap changer)  
  • Vector Group: YNd11
  • Frequency: 50 Hz
  • Reference standard: IEC

340 MVA Power Transformer

  • Type: Three-phase – Generator step-up
  • Rated power: 340 MVA
  • Cooling: ODAF
  • Voltage ratio: 400000 ± 8 x 1.25% / 18 kV (with on load tap changer)
  • Vector Group: YNd11
  • Frequency: 50 Hz
  • Reference standard: IEC

A detail of the conductors supplied to Tamini (55 tons in total)

Ctc pwc Nomex t910 dupont

For the realization of these two important projects, various CTC and PWC conductors produced by our company were supplied:

  • CTC with 7 enamelled wires insulated with 18 Nomex T910 insulating tapes
  • CTC with 17 enamelled wires insulated with 10 T910 Nomex tapes
  • CTC with 11 enamelled wires insulated with 11 T910 Nomex tapes
  • PWC 7x16mm insulated with 17 T910 Nomex tapes
  • PWC 1.7x11mm insulated with 12 T910 Nomex tapes

Operational success and reliability over time

The transformers, completed without problems thanks to the use of high quality semi-finished products supplied by De Angeli Prodotti, have been operational for several years, receiving great satisfaction from the end user. The collaboration between De Angeli Prodotti and Tamini has demonstrated the value of advanced technology and innovation in the energy sector, offering solutions that meet the most stringent needs of the market.

In conclusion, De Angeli Prodotti continues to lead the industry with cutting-edge products, contributing to the progress and sustainability of the global energy sector. The fruitful collaboration with prestigious partners such as Tamini and Dupont is testimony to the quality and constant commitment of the company towards excellence in providing advanced solutions for power transformers.

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