The South African market is steadily recognising Marthinusen & Coutts’ capabilities in the area of restoration and modernisation of old electrical equipment to “as new” status. This capability is also associated with significant cost savings.
Northam Platinum recently acquired a used 4300kW winder DC motor to drive the hoist that is due to be installed in the new Number 3 Shaft for the Zondereinde Western Extension of the mine near Thabazimbi, Limpopo.
At the beginning of this year DRA, the consulting engineers for Zondereinde, contracted M&C to inspect and test the 37-year-old motor and drive shaft and perform any repairs that were required to be done. M&C was also commissioned as part of the contract to manufacture a number of key spare parts for the motor.
M&C’s Large Motor repair facility in Benoni, which is equipped to handle very large rotating machinery, performed the work, completing it in mid-November this year.
The motor’s 42t armature was found to be in good working order, while the frame’s interpole coils and brushgear were partially refurbished and cleaned.
M&C applied reverse engineering methods to manufacture the spare parts for the motor, which comprised three each of field coils, interpoles and pole shoes, plus a full set of 24 damper bars – eight for each of the three spare pole shoes.
“The units were extremely complex to assess and it was a challenge to manufacture all the new spares and replacement parts required,” said Rudi Els, General Manager of M&C’s Power Generation & Large Motor repair facility.
“There were literally thousands of different parts, which called for a great deal of attention to detail and specialist reverse engineering. It was also a major task to document and control the status of all these parts,” he added.
The 38t 10.5m long drive shaft was found to be in good order.
