The City of Ekurhuleni’s electricity department says theft, vandalism and load-shedding resulted in Ward 27, which includes Northmead, Airfield, Ebotse, Morehill and parts of Rynfield, experiencing rolling blackouts last month.
The Benoni City Times reported on March 7, that the affected areas experienced 11 days without electricity in February.
At the time, Ward 27 Clr Lornette Joseph said calls to key stakeholders, including Executive Mayor Nkosindiphile Xhakaza, MMC of Energy Mzayifani Ngwenya and the city manager, Dr Imogen Mashazi, along with the head of the department and chief engineer, to engage in with the community during a public meeting went unanswered.
On March 3, CoE spokesperson, Zweli Dlamini responded to questions regarding the outages, stating that continuous monitoring measures have been implemented to prevent future occurrences and to ensure network reliability.
Theft and vandalism
Responding to the outage that occurred on February 1, which left Rynfield, Ebotse, parts of Morehill and Northmead without power for between 48 and 70 hours, Dlamini said theft and vandalism at the Rynfield substation was to blame.
“Critical infrastructure, including transformers, cables and the switchgear, was damaged and components thereof were stolen,” he said.
“A detailed on-site assessment was conducted and emergency teams were deployed to repair damaged infrastructure and replace stolen components in order to restore power.”
• Transformer 1 – the unit was damaged beyond repair by vandals thus making power restoration impossible.
“As a result, repair and replacement efforts were initiated to restore functionality,” said Dlamini.
• Transformer 2 – equipment failure of 185mm² of cables, between the transformer’s medium-voltage side and the 11kV switchgear led to a further interruption of services.
Electrical tests were conducted on the affected transformer and cable repairs were carried out, ensuring that power supply to all clients was restored.
Cable faults
On February 7 an estimated 7 900 households were once again left without power due to the failure of a 132kV oil-filled cable.
Dlamini explains the outage was caused due to a significant drop in oil pressure.
“The loss of pressure compromises the cable’s insulation, resulting in an electrical fault. It is therefore necessary to ensure that the cable is isolated from the electrical network,” he said.
“A technical team conducted an assessment to determine the extent of the issue and to identify corrective measures. As part of the restoration process, the cable was repressurised to restore proper insulation and cooling, followed by testing to ensure stability before it was safely re-energised.”
Power to the affected areas was fully restored in the early hours of February 10.
Load-shedding
Speaking about the impact of load-shedding on the city’s already buckling electrical infrastructure, Dlamini said one of the major challenges is cold load pick-up (CLPU).
“This refers to the sudden surge in electrical demand when power is restored following an outage,” he said.
“This occurs due to electrical loads that were running before the outage simultaneously restarting.”
Impact of CLPU following load-shedding includes:
• High inrush currents – Once power is restored, household appliances such as motors, heating systems and air conditioners draw higher-than-normal starting currents, which can overload the system. “When all electrical apparatus come online as soon as scheduled load-shedding comes to an end the impact of high inrush currents results in prolonged power outages,” said Dlamini.
• The impact of load-shedding on power cables – “Load-shedding has significant consequences on electrical infrastructure, particularly on power cables. The repeated switching off of electrical supply causes thermal and mechanical stress, which can lead to accelerated wear and failure,” he said.
“This leads to an increased risk of cable failures, creating electrical surges that stress cable insulation. These surges can lead to insulation breakdown and eventually, complete equipment failure, requiring costly repairs or replacements.”
He continued by saying the power interruption on February 24, affecting Struben and Lessing streets, along with all seven of the Rynpark retirement villages, occurred during the switching on process after scheduled load-shedding.
“Due to an increased number of outages reported via the CoE Customer Service Centre, restoration processes were delayed,” said Dlamini.
To date a third request by Joseph for a public meeting has gone unanswered and Dlamini stating that a meeting of this nature can only be scheduled by the mayor’s office.
“I will continue applying pressure for a meeting with all the relevant stakeholders,” said Joseph.
“The community is entitled to getting feedback as well as answers about how these persistent outages will be addressed.”
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