Primary protection

Eletrobras, a major Brazilian electric utilities company, is completing major projects throughout Brazil using NOJA Power’s Automatic Circuit Reclosers (ACRs).

Eletrobras Distribution Piauí, a subsidiary of Eletrobras, concluded another phase of a project that aims to increase the reliability of Teresina’s (Piauí’s capital) power distribution networks. The utility reached 100 installed Automatic Circuit Reclosers (ACRs), which reduce the occurrence of power outages.

“The recloser is a protective equipment that, when it detects faults (short circuit) on the network, cuts off the network in seconds and then makes repeated attempts to re-energise the line, in order to avoid long periods of power failure,” said maintenance manager from MV and LV Abraão Galeno.

“Statistics show that 70–90% of faults in the electricity distribution system are temporary, so stopping the effect a few milliseconds after the occurrence, the recloser then acts to restore the electrical system automatically, without any operator assistance,” said Abrãao.

Electrobras Distribution Piauí is extending this action to all Piauí, in order to reduce complaints by customers regarding power outages.

To improve energy supply, Eletrobras Acre Utility (another subsidiary of Eletrobras) is investing about R$10 million (AU$3.77 million) in 212 new NOJA Power ACRs on the electrical distribution networks of the state of Acre in Brazil. The project is being carried out by the distributor’s expansion board with resources provided by the World Bank.

NOJA Power’s control system allows the recloser to perform automatic trips to open and close circuits in order to protect the electrical system. The device minimises the affected area during interruptions, ensures a higher fault interruption capacity (usually an overload caused by short circuits) and provides increased security and safety for installations and people.

The first step of the project will begin in July with the installation of the ACRs. The second step includes configuring the automation process.

“With these measures, the prospects for improving the quality of supply of energy for the state of Acre are greatly increased, especially in the winter period, because we are tripling the number of these devices on our distribution network, greatly increasing the automation process,” said Joaquim Rolim, operations director of Eletroabras Acre Utility.

Eletrobras Distribution Amazonas (EDA) installed four new NOJA Power OSM reclosers in June 2016 in Humaitá’s substation, strengthening the overall primary protection of the 13.8 kV equipment. NOJA’s ACRs replaced old oil circuit breakers, which are already out of date and have been in use for over 25 years. This new equipment increases the reliability of protection of the distribution system and generation at Humaitá.

NOJA Power’s OSM series ACRs benefit from the use of vacuum interrupters and solid dielectric insulation instead of the environmentally unfriendly oil or sulfur hexafluoride (SF₆) gas used in sectionalisers and older recloser products. Another key feature of the OSM series is its stainless steel enclosure that forms the only solid dielectric unit with controlled internal arc fault venting on the market.

The four reclosers installed in Humaitá are part of a package of 120 reclosers acquired by the Eletrobras Utility.

“All new equipment will be installed in our substations throughout the first half of 2016. It is a major breakthrough in the security of our energy system network and I must highlight the importance of the support received from the Ministry of Mines and Energy and the commitment of the minister, Mr Eduardo Braga,” said José Francisco Albuquerque da Rocha, operation director EDA.