Electromechanical equipment manufacturer and ACTOM division Marthinusen & Coutts Zambia (M&C Zambia) noted, in a press release last month, that a smelter based in the Copperbelt had requested that it provide an in-country repair solution on the smelter’s two critical 4.5 MW compressor motors, with three weeks to complete the overhaul and commission the motors.

The scope of the work included the dismantling, cleaning and assessment of all parts, dynamically balancing the rotors at operating speed using M&C Zambia’s own 12-t balancing machine, supplying new bearing assembly parts, assembling the motors and no-load testing and laser aligning 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,” explained M&C Zambia GM Eugene Lottering.

He noted that M&C Zambia consequently requested the M&C workshop in Cleveland, Johannesburg, to supply partial discharge treatment of the stator coils and to manufacture the replacement stator wedges.

To ensure that all the work complied with international standards, M&C also sent a senior technician from Johannesburg to assist with the local team on the contract.

Lottering noted that the M&C Zambia team is sufficiently experienced to approach and action various stages throughout the motor overhaul process.

“We 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 elaborated.

He added that the installation of the motors on-site turned out to be a complicated procedure, especially when aligning the motors to the compressors.

The motors were tested on load, recording satisfactory vibration levels of below 1.34 mm a second, and were successfully installed and commissioned three days before the scheduled deadline for completion.