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Rapid turnaround on mill motor repair
Marthinusen & Coutts, a division of Actom, recently repaired two
large mill motors for leading uranium producer, Rössing Uranium
in Namibia; a company celebrating 40 years of production this year.
Marthinusen & Coutts’ field service team was requested by Ross-
ing to inspect two brush mill motors on site.The team found that the
starting cage winding on one of the motors had moved and rubbed
against the stator winding, while an insulation test conducted on the
secondmotor indicated that the stator windingwas down to earth.This
necessitated having both motors repaired at Marthinusen & Coutts’
facility in Cleveland. In view of the fact that no spare motor would be
available to the mine in the event of a further breakdown while the
two sparemotors were being attended to byMarthinusen & Coutts in
Johannesburg, the first of the two 1 586 kW 3 300V, 187,5 rpm, brush
motors to be repairedwas treatedwith the greatest urgency to ensure
that it was returned to the mine as quickly as possible.
“We therefore designated it as being ‘a breakdown’ and the re-
pairs on it were carried out as soon as it was received at our plant in
October last year.The repairs were completed within three months
and the motor was returned to the mine early in January this year,”
Craig Megannon, Marthinusen & Coutts’ general manager, says.
The repairs carried out on the two motors consisted of rewinding
the stators incorporating use of a resin-rich winding system, over-
haul of the rotors and complete replacement of the rotors’ electronic
diode and synchronising hub.
“Application of the resin-rich winding system for the stator rewinds
necessitated having to manufacture special customised press boxes
for curing the cells. A critical part of this was ensuring that the di-
mensions of the cells were 100% correct so that they fit into the core
slots exactly. A coil reset jig also had to be made to enable us to
manufacture the coils to the correct shapes,”Megannon commented.
Repair of the second motor was completed at the end of March.
In addition to the stator rewind with resin-rich windings, the rotor
was overhauled and the quadrants on a damaged damper winding
of the rotor were replaced.
Enquiries: Richard Botton.Tel. +27 (0) 11 607 1700
or email
ROUND UP DRIVES, MOTORS + SWITCHGEART AN FORME UBSTATIONS
9091 - EMA 2016 VIS HP AD CROWN PUBLICATIONS 180X130_PATHS.indd 1 2016/06/20 9:11 AM
Alpheus
Mtshali, from
Marthinusen
& Coutts, with
the 1 586 kW
187,5 rpm,
3 300 V,
278 A stator.
37 August ‘16 Electricity+Control