In August 2022 Marthinusen & Coutts Zambia was requested by a smelter based in the Copperbelt to provide an in-country repair solution on two critical 4.5 MW compressor motors. It was given only three weeks in which to overhaul and recommission the motors.
Dynamic balancing of the rotors at operating speed was done using M&C Zambia’s in-house 12-tonne balancing machine.
The scope of work involved the dismantling, cleaning and assessment of all parts, dynamic balancing of the rotors at operating speed using M&C Zambia’s in-house 12-tonne balancing machine, supply of new bearing assembly parts, assembly of the motors and no-load testing and laser aligning the motors on site.
“On dismantling both motors we identified that the stator coils indicated partial discharge and the stator wedges had deteriorated significantly over time. We consequently requested the M&C workshop in Cleveland, Johannesburg, to provide partial discharge treatment of the stator coils and to manufacture the stator wedges that needed to be replaced,” said Eugene Lottering, General Manager, M&C Zambia.
To ensure all the work complied with international standards, M&C also sent a senior technician from Johannesburg to assist the local team on the contract.
“Our team is well experienced in how to approach and action the different stages throughout the overhaul of such motors. We have successfully completed various medium voltage overhauls up to 4 650 kW. The motors were no-load tested at 11 kV with exceptionally good results and the customer then gave us the go-ahead to commission the motors,” Lottering added.
He highlighted that “Installing them on site turned out to be a complicated procedure, especially the alignment of the motors to the compressors.”
The motors were finally tested on load, recording satisfactory vibration levels of below 1.34 mm per second.
“The motors were successfully installed and commissioned three days before the scheduled deadline for completion,” Lottering noted.
For more information visit: www.mandc.co.za
