Pretoria getting load rotation after pylons collapse
The City of Tshwane will start implementing load rotation (also called load reduction) to provide areas that have been left without electricity for multiple days with some intermittent power.
The collapse of seven pylons holding 132kV high-voltage power lines occurred during a storm at roughly 21:00 on Sunday, 9 April 2023.
The incident plunged large parts of Pretoria East, Pretoria North and a portion of Centurion into darkness.
It also forced the closure of the N4 highway until late on Monday afternoon, as a section of the cables had fallen across the road and caused several accidents.
Many areas have since had their power restored due to the municipality diverting electricity from alternative substations.
However, over 40 suburbs remained without power as it was not technically possible to divert their electricity feeds to other substations without causing overloads.
To address this, the city’s energy and electricity technical team has now taken the “extraordinary” step to feed the Waltloo and Mamelodi Substations with electricity from the Njala infeed substation.
“Ordinarily, Waltloo and Mamelodi substations are fed by the Pumulani substation, which has also been affected by the power outage which occurred on Sunday night in the wake of suspected vandalism of a pylon along the N4 east freeway,” the city explained.
As a result, it will have to implement load rotation in areas with power to re-channel electricity to areas that have experienced a prolonged outage.
Municipal staff working to remove cables that fell over the N4 Highway after seven power pylons collapsed on Sunday, 9 April 2023.
Tshwane said the energy and electricity technical team changed settings and performed protection grading at the Njala infeed substation on Tuesday evening, completing the work on Wednesday morning.
“The switching team was dispatched to the Waltloo and Mamelodi Substations this morning to start energising transformers to soak, after which they added the load gradually, while constantly monitoring the load.”
“Gradual switching will commence shortly.”
The municipality said that this was an interim measure that would likely overload the system, resulting in possible trips.
“To obviate possible trips due to overload, the city will implement a 4-hourly load reduction in some areas of Watloo, Mamelodi (1,2,3), Pumulani and Koedoespoort supply area,” Tshwane said.
In addition, the load rotation will impact parts of Tshwane region 2, 3, 5 and 6, which include the following areas:
- Region 2 — Hanmmanskraal, Montana, Sinoville, Temba, Wonderboom
- Region 3 — Brooklyn, Hatfield, Pretoria CBD, Pretoria West
- Region 5 — Cullinan, Rayton, Roodeplaat
- Region 6 — Eersterust, Mamelodi, Pretoria East, Shere
The city acknowledged the “pain of load reduction” on top of load-shedding being implemented by Eskom but wanted to ensure the even and balanced provision of power to all residents.
The city said it would communicate the specific schedule for each area in due course.
Eskom is supplying and helping Tshwane rebuild the power pylons. The state-owned power utility told Afrikaans newspaper Beeld the work could take up to five days.
The utility has previously said the estimated cost of rebuilding a power pylon was between R3-4 million, which would put the total cost for seven pylons at between R21-R28 million.
While the pylons are designed to withstand powerful winds, it is suspected that the structure of at least one of those that collapsed had been severely weakened by theft and vandalism of some of its supports.
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