In August 2022 Marthinusen & Coutts Zambia was requested by a smelter based in the Copperbelt to provide an in-country repair solution on their two critical 4.5MW compressor motors. It was given only three weeks in which to overhaul and commission the motors.
The scope of work involved was to dismantle, clean and assess all parts, dynamically balance the rotors at operating speed using M&C Zambia’s own 12t balancing machine, supply new bearing assembly parts, assemble the motors and no-load test and laser align the motors on site.
“Upon dismantling both motors we identified that the stator coils indicated partial discharge and the stator wedges had deteriorated significantly over time. We consequently requested M&C’s workshop in Cleveland, Johannesburg to supply partial discharge treatment of the stator coils and to manufacture the stator wedges that needed to be replaced,” said Eugene Lottering, M&C Zambia’s General Manager.
To ensure that that 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 various stages throughout the overhaul of these motors. We successfully completed various medium voltage overhauls up to 4650kW. The motors were no-load tested at 11kV with exceptionally good results and the customer then gave us the go-ahead to commission the motors,” Eugene explained.
“Installing them on site turned out to be a complicated procedure, especially the alignment of the motors to the compressors,” he added.
The motors were finally tested on load, recording satisfactory vibration levels of below 1.34mm per second.
“The motors were successfully installed and commissioned three days before the scheduled deadline for completion,” Eugene concluded.
