Modern Mining February 2023

However, the teams were confronted, prior to the shutdown, with unexpected complications that had to be first resolved before any of the GO procedures could be carried out.. Special equipment was provided for removal of the rotor out of the stator core, on a sliding rig with trolleys running on a track to bring it out into a cen tral position on the frame structure, from where it could be lifted by a 120 t mobile crane for transport to the workshop. The rotor threading frame structure, comprising three steel A-frame pedestals anchored onto con crete plinths, was intended to provide support to the rotor threading structure used to remove – and later re-install – the rotor. “As a precaution before commencing the work, we assembled and checked the threading frame structure in our workshop. All the welds on the A-Frame pedestals failed inspection and had to be re-welded,” said Chamberlain. “On site we found that the structure did not fit, as the cable racks and electrical boxes were in the way, so the railway beam was cut away to clear these obstructions. Furthermore, the railway track was inadequate for supporting the weight of the rotor. It was also necessary to manufacture a new more stable coupling side trolley and modify the skid

plate on which the sliding skid runs, to ensure proper protection of the stator windings during removal of the rotor.” Despite the challenges, the contract was com pleted within the shutdown period with days to spare. 

February 2023  MODERN MINING  29