In what has been described as the largest winding installation ever conducted in South Africa, Marthinusen & Coutts, a division of ACTOM, has completed a major repair at Eskom’s Ingula pumped storage hydro-electric plant.
The contract involved the complete rewind of a 373 MVA stator for one of Ingula’s four 14-pole motor generators. According to Richard Botton, MD of Marthinusen & Coutts, the 342 MW unit is among the biggest in South Africa with a core diameter measuring 5 m, a core length of 3,2 m and a rotor mass of 500 t.
“As the stator was located deep in the turbine floor, all the winding was required to be conducted on site,” says Botton. “In this complicated repair, each replacement coil set was fitted, connected and brazed on-site from pre-manufactured and pre-packed components supplied by the OEM. The most painstaking process, conducted to the highest standards, was the resistive brazing on 1 824 joints.”
Marthinusen & Coutts carried out the work with a 14-man team, completing the work in November 2018 after 100 days on site. Their extensive preparation included the establishment of training jigs at its Johannesburg facility, allowing customised training for all technicians involved in the mammoth project.
“We also conducted detailed testing, and refurbishment where necessary, of all the winding equipment we would use on site,” he says. “This contributed to smooth and uninterrupted operations, making us self-sufficient in rolling out the contract.”
Working closely with OEMs and Eskom, Marthinusen & Coutts took full ownership of the rewind project from start to finish, he notes. The contract was successfully completed on-time with all test criteria well within specification.
“With our in-country expertise, supported by our Centres of Excellence in Benoni and Cleveland, the project showed the world class capability of Marthinusen & Coutts,” says Botton. “We could also contribute our specialised equipment and supply chain – elements that often present a challenge to foreign service providers trying to conduct this kind of project work in South Africa.”