After some difficulties imposed by COVID-19, last February 2021 the treatment campaign in Saudi Arabia kicked off. This is an activity out of the ordinary for the amount of electrical equipment to be treated, 23, their size, up to 130 tons of oil, maximum voltage and power (up to 380 kV and 500 MVA), and consequently the total amount of insulating liquid to be treated: 1,750,000 kg. The transformers are mainly located in the central area of the Saudi Kingdom and Riyadh.
Sea Marconi, which received the order thanks to the collaboration with the local technological partner GCC Lab, will carry out selective depolarization treatments from DBDS, aimed precisely at reducing the concentration of DBDS (in the oil), the main cause of the corrosive sulfur phenomenon.
The 23 transformers have a contamination between 60 and 170 mg/kg of DBDS; Sea Marconi guarantees the customer that one year after treatment, the contamination will be <10 mg/Kg. The samples before and after the intervention will be certified and validated by a third party laboratory.
All transformers will be depolarized on-load, which means that the transformer remains in service and loaded for the entire duration of the treatment, using the typical Sea Marconi method: closed circuit, without even partial emptying of the transformer. In doing so, the hot oil constantly flows from the transformer to our integrated treatment unit which progressively brings it back to optimal conditions (in accordance with IEC 60422 Ed. 4-2013, CIGRE 378 – 2009 art. 4.2). Thanks to the use of multi-connection units (designed and built internally) it is possible to treat at the same time the oil contained in the accessory units of the transformer (eg. cable boxes) and also “clean” the dead zones inside the transformer.
The Sea Marconi treatment plant dedicated to this campaign (Smart DMU GAMMA) is one of the most advanced in the sector, it works 24 hours a day, 7 days a week, with only daytime technical staff; in fact, the system is able to work independently and possibly send alarms to available operators. Not only that, thanks to the SCADA system (Supervisory Control And Data Acquisition), the Sea Marconi engineers present in the control room in Turin can monitor the performance of the system and interface in real time with their operators on site for consultancy, training or troubleshooting.
As of today, April 14, 2021, the depolarization of the first transformer is about to end with an excellent result, it has gone from 148 to <5 mg/kg of DBDS. These performance are the result of a series of winning factors, on the one hand there is an extraordinary knowledge of the sector, on the other the use of patented materials and technological solutions of absolute excellence.