In the city of Salto (Uruguay) on 10, 11 and 12 November 2013 the International Power Transformer Workshop organised by CUGRE (Comite Uruguayo De Grandes Redes Electrica), the Uruguayan CIGRE took place. Sea Marconi has been invited to the event as international expert on the phenomena of degradation of the insulating liquids, on the topic of corrosion in general and in particular on the type C3 oil corrosion (SDBP & corrosive sulfur), i. e. linked to the by-products of the degradation of sulfur.

Download the brochure of the event from the CUGRE site

On this topic, Sea Marconi developed, indeed for the Uruguayan UTE (a state company for the transmission of electricity) an ad-hoc expertise, offering a substantial contribution for the prevention and mitigation of damages on strategic equipment mainly in the field of generation and transportation of power. Critical factors surfaced relative to equipment over 20 years in operation, where the rate of failure is progressively increasing and this required the capability of developing an ad-hoc diagnostic coverage to identify specific countermeasures. Another criticality being underlined in the last few years, not only in Latin America, is the increment in the failure rate, (in the first year for a few types of equipment, up to 25 %) on new pieces of equipment produced by suppliers just appeared on the market characterised by low prices and low quality.

UTE was also supplied with the new kits SM-TCS (Total Corrosive Sulfur) together with the relevant training sessions, so that the Uruguayan technicians can perform a field or laboratory quantitative determination for cases C1 (Corrosion with DBDS), C2 (Corrosion without DBDS), C3 (Corrosion by degradation by-products of sulfur), C4 (Corrosion by dissolved metals without sulfur).
The workshop was organised not far from the Salto Grande hydroelectric power station, the largest in Uruguay, with an output of 1,890 MW. The Salto Grande power station, built in the 70? With a decisive Italian contribution (Impregilo constructions) is the first infra-structural project developed in South America by a by-national entity, with the participation of Uruguay and Argentina.

Sea Marconi calls this case as SCBP (Sulfur Combustion ByProducts) & Corrosive Sulfur.

“The oil regeneration process plant involves the high temperature reactivation of sorbent and fuller earth column by uncontrolled combustion. The Sulfur Compounds naturally present (DiBenzoThioPhene – DBTP, etc.) in the Oil and additives (DBDS, etc.) are decomposed in Sulfur Combustion ByProducts (such as corrosive H2S, Mercaptans, etc.) forming Sulphides CuS, Cu2S, Ag2S, etc.”. Ref. other case histories such as National Grid, ABB, etc.

Download the flier PDF: Sea Marconi Treatments Vs Fuller Earth treatments ENG (377.5 KiB)

*CDP Process^® for PCBs/POPs chemical dehalogenation; CHEDCOS for DBDS & Corrosive Sulfur Selective Depolarization

Post Failure diagnosis on a Grid Transformer showed signs of electric arcs on tap selector contacts. The failure has been caused by the formation of Corrosive Sulphides as CuS, Cu2S, Ag2S, etc. Indeed «At relatively high temperature, sulphur-containing oil molecules may decompose and react with metal surface to form metal sulphides» (IEC 60422 Ed. 4 – 2013 art. 5.17). This mechanism started together with the oil regeneration process with reactivation of sorbent and fuller earth column by uncontrolled combustion (> 370 °C). The Sulfur Compounds naturally present (DiBenzoThioPhene – DBTP, etc.) in the Oil and additives (DBDS, etc.) are decomposed in Sulfur Degradation ByProducts. Other Ref. National Grid (UK), ABB (Sweden), 2010 Doble Conference (USA)

• 45 years of Innovation for Life Cycle Management of Oils & Transformers;
• Solutions based on Global and Integrated Approach, Case histories, State of the Art, IEC Standards, CIGRE Guidelines, Stockholm Convention on POPs (Persistent Organic Pollutants);
• Opportunity for prevention and/or mitigation of losses and risks for the asset, workers, public health and environment;
• Focus on hot topics and priorities for strategic electrical equipment filled with insulating fluids;
• Diagnosis (> 150,000 cases) and Integrated Treatments (> 700 Power Transfos – 2012) with DMU (25 Decontamination Mobile Units), guarantee independent expertise, reliability, quality control (ISO 9001-2008, ACCREDIA ISO 17025), traceability, economic benefits, environmental protection, social, stakeholders and insurance relationship.