Every year, Neoenergia carries out an important maintenance operation of its electrical network installed near the coast. it is the washing of the network, as a part of the preventive maintenance planning of Neoenergia's concessionaires and is part of the summer plan, carried out with the purpose of improving network reliability in coastal areas during the summer season. In total, between September and December 2020, the network will be washed in 27 municipalities in the states of Bahia, São Paulo and Rio Grande do Norte, corresponding to more than 15 thousand points of network benefited.
The washing is carried out with the network energized, that is, it does not cause the interruption of the energy supply to the customers. Among the main objectives is the structure safety, by reducing the effects of the existing salinity by the sea. "This is important because the salt mist is the most harmful to the network operation, as it contains a large amount of mineral salts, which are energy conducting elements. Thus, the accumulation of salinity in the insulators of poles and substations ends up affecting the network integrity, causing faults and short circuits," explains Elektro’s Sector manager of South Coast, Wilhelm Guilherme.
The washing is done in three states of the company's concession areas: Bahia, São Paulo and Rio Grande do Norte, due to the impact of the sea mist in these regions. "We assess which areas are most affected by the action of salt mist and we schedule the washing before the beginning of summer, because we notice that at this time there is an increase in energy consumption, especially in places that host tourists because of the beach. Thus, it is important that the network is in good standing to accommodate the growth in energy demand", says Márcio Caires, Operations Superintendent for the Southern Region of Coelba.
An additional point taken into consideration when starting to wash the network is the rainy season in the Northeast, because the combination of saline pollution and rainwater can damage the correct operation of the insulators, which are responsible for preventing the electric current from escaping from the network". Contrary to what many people may think, rain does not wash the network properly, mainly because it contains energy conducting minerals. That is why special water - demineralized - is used for washing the network", says Pammella Santos, electrical engineer of Cosern's West-Seridó Network Expansion and Preservation Unit.
The washing is carried out using a tank truck, supplied with demineralized water and equipped with insulators so as not to transmit power. In addition, the field team must be properly equipped with personal protective equipment. To ensure the safety of the activity, water jets are intermittent, i.e., they are discontinued at regular intervals in order to prevent a possible leakage of power from the grid. Therefore, it is important to emphasize that the washing of the electrical network is a procedure that only the concessionaire’s technicians are authorized to perform.
For Elektro, where the activities started in September, 10 cities of Sao Paulo will be benefited with the washing of the network by December - Ilhabela, Ubatuba, Ilha Comprida, Cananéia, Iguape (Barra do Ribeira), Itanhaém, Mongaguá, Peruíbe, Bertioga and Guarujá. A total amount of 4,273 points of the network will go through the procedure and around 13 thousand liters of water will be used in the process.
In Rio Grande do Norte, Cosern‘s concession area, the washing will be performed in 15 cities – Mossoró, Areia Branca, Porto do Mangue, Baraúna, Sibau, Grossos, Serra do Mel, Tendências, Macau, Guamaré, Natal, João Câmara and Ceará-Mirim. In the state, the schedule lasts from October from December, or up to the beginning of the first rains. 9,500 structures on the coastal strip will be washed using a total of 75,000 liters of demineralized water.
At Coelba, the washing of the network extends until December and benefits two cities – Mata de São João (Praia do Forte, Costa do Sauípe, Diogo and Santo Antônio) and the Atlantic coast of Salvador (between the neighborhoods of Praia do Flamengo and Barra). 16 thousand liters of demineralized water will be used to wash around 1,600 structures in these locations.
In Pernambuco, operation area of Celpe, the network washing is not part of the preventive maintenance schedule, but it has several other initiatives carried out with the objective of ensuring the network integrity in coastal areas. "The construction of the networks in these locations complies with construction standards with specific materials, such as copper cables and porcelain insulators, compatible with the presence of a higher salinity index as compared to other regions of the state", says the Celpe’s manager of Operations of the Metropolitan Sector, Osvaldo Tavares.
Inspections for prior identification of faults in the electrical network are performed throughout the year at the four distributors and, during the period preceding summer, the focus is increased for coastal regions. Among the initiatives carried out for this purpose are the inspections with thermal imager, responsible for detecting temperature differences in the network. Should any hot spot is found, future fault becomes probable. Thus, maintenance is preventive and predictive, by identifying a fault before its occurrence to execute the proper repair. The thermal imager is attached to the upper part of the car, which is moved through the inspected areas with an operator reading the networks on a screen, which facilitates and speeds up the activity.
Actions aimed at providing a higher quality and safer energy supply also include visual inspection, to identify possible failures, and replacement of network components due to oxidation due to sea mist, such as transformers. In addition, pruning of trees may be required as part of preventive maintenance planning that is intensified in summer areas in the last quarter of the year. In some situations, the branches reach the wiring of the electrical network, causing interference in the energy supply, which is why it is important to perform periodic pruning.