Hydro power plant

Nameplate data of transformer:

Transformer: GSU transformer
Power [MVA]: 30
Voltage [KV]: 130
Oil mass [Kg]: 58.000
Oil type: paraffinic

Solution: Selective Depolarization treatment (Chedcos) performed on-load (transformer fully load during the treatment)

As already anticipated by an article of June 2010 published on this web site, Sea Marconi, in collaboration with the University of Turin¹ (Dept. of Analytical Chemistry), University of Missouri (“Rolla”)² and the Serbian research Institute “NIKOLA TESLA”³, is engaged in a research project promoted by the Ministry of Economic Development favouring the integration between Universities and enterprises at international level.

The studies, started on 16^th November 2009 are in the final stages; the end of the activities is scheduled on 16^th May 2011.

The “Project n° 31. Life Cycle Assessment study of metal contaminated large power electrical apparata” has the objective of deepening the phenomenon of the formation and presence of metal contaminants in insulating liquids used in high power electrical equipment (transformers, reactors, rectifiers) used in the generation, transmission, distribution and application networks of electric power. This topic, already subject of investigations by normative groups in this sector (IEC, Cigre, ASTM, Doble, etc.), can cause the degradation of oils and equipment also with catastrophic consequences. The financial impact on international scale of such failures and the resulting blackouts, is in the range of billions of Euros.

After more than five years since the discovery by Sea Marconi and Terna of DBDS (DiBenzylDiSulphide), a sulphurised compound responsible for failures due to corrosive sulphur, it surfaced that corrosive oils exist also when such substance is not present. This involves the importance of the research of other potentially corrosive sulphurised substances in the oil and the evaluation of their effects in presence of copper and insulating paper.

For what the first results of the research are concerned, it has been pointed out, first of all, the considerable corrosive action of sulphurised compounds such as sulfoxides, which role in the formation of copper sulphide (CuS) till now has been considered secondary. It has also been observed, that as well oils considered not corrosive show the capacity of transferring important amounts of copper on the cellulose. Finally, through the examination of real samples, it was possible to deduct that the dielectric losses of the oils are mainly influenced by the fraction of soluble copper rather than by the particle one.

This project has seen Sea Marconi on the front line with the objective of deepening, in a pioneering way, dynamics still not clear on the international scenario with the purpose of identifying solutions to extend the life cycle of electrical equipment, while respecting and protecting the environment.

¹Prof. Corrado Sarzanini

Università di Torino – Dipartimento di Chimica Analitica, via P. Giuria, 5 – 10125 TORINO (ITALIA)

²Prof. Shubhen Kapila

Center for Environmental Science and Technology Missouri University of Science and Technology (A Campus of the University of Missouri)

Rolla, MO 65409 (US)

³Dr. Jelena Lukic,
Elektrotehni?ki institut, “NIKOLA TESLA”, Koste Glavini?a 8a Srbija, 11000 Beograd