Company Announcement - Marthinusen & Coutts recently performed a rush job for sugar producers Tongaat Hulett in repairing the rotor of the 20 MW salient pole synchronous alternator at its Xinavane mill near Maputo, Mozambique. The division carried out the complex task at its Cleveland, Johannesburg, facility in just over three months. It involved a complete rewind of the rotor, which has a cruciform-type winding configuration.
“It was complicated by the fact that we found it necessary to redesign the winding and insulation,” Craig Megannon, general manager at Marthinusen & Coutts, explains.
“The original coil had developed a fault due to the fact that it had been vacuum pressure impregnated, which by forming it into a solid block caused differential expansion between the copper windings and the steel of the rotor body. We solved this problem by introducing thicker insulation and thinner copper windings, which were neither VPI’d nor glued to the pole body. “This achieved the desired result, as proven by the tests we carried out on the rotor windings on completion of the job,” Megannon says.
With 57 years of extensive experience in the local and global market, Marthinusen & Coutts undertakes both electrical and mechanical repairs, overhauls and complete refurbishments.