Question NW271 to the Minister of Cooperative Governance and Traditional Affairs
03 April 2023 - NW271
Horn, Mr W to ask the Minister of Cooperative Governance and Traditional Affairs
What (a) has been found to have caused the explosion of the municipal electrical substation situated on the corner of Rooispan Street and Klaradyn Avenue in Bloemfontein on 13 December 2022, which caused an electrical outage in the area lasting more than 92 hours and (b) steps have been taken to prevent a re-occurrence?
Reply:
(a ) Root Cause Analysis. The root cause of the prolonged power failure in Pellissier was the insulation failure of the 3 x single core cables constituting the 11kV blue phase cables connecting the 11kV side of transformer no.1 to the 11kV switchgear. The 11kV fault on the Oberholzer feeder only aggravated the matter but it was cleared without any damage to the cable feeding Oberholzer feeder from Pellissier DC.
(b ) Steps taken to prevent a re-occurrence
The 2 x 33/11kV transformers were tested and they tested clean at Pellissier DC. The 33/11kV Transformer no. 2 was re-energized and all load was taken by 14h30 on Saturday, 11th of November 2022. This was with the exception of the faults experienced at the Bitterbessiebos substation, Vierperdewa, and Lantern miniature substations.
The 33kV circuit breaker on Transformer 1 at Pellissier DC was badly damaged. This circuit breaker is being replaced with the 33kV circuit breaker that was utilized for the 33kV General de Wet feeder. The cable on that feeder has been out of commission for an extended period of time. The 33kV circuit breakers are old and they will be replaced when the 33kV Switchgear bid is appointed for.
The Protection on the 33/11kV Transformer no. 1 at Pellissier DC is currently being upgraded with Numerical Protection Relays so that it can be of the same technology as the 33/11kV Transformer no. 2. This transformer will be out of commission until the upgrades are completed.
Pellissier DC is currently carried by the 33/11kV Transformer no. 2 and the loading on the transformer is in order. The damaged NER was replaced, and the replacement NER is now connected and hot commissioned. Pellissier DC is now stable, and the redundancy will be regained when the 33/11kV Transformer no. 1 is back in service.
End.