Electricity + Control August 2017

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29 Electricity + Control AUGUST 2017
round up
Containerised electrical solution to drive mill on mine in Mali
Shaw Controls, a Zest WEG Group company, reports the suc-
cessful completion of its contract to supply a containerised elec-
trical solution to a gold mine in West Africa. Kirk Moss, medium
voltage manager at Shaw Controls, says the containerised solution
will supply power to drive a mill on this new mine.
“Containerised electrical solutions are becoming increasingly
popular as these allow for speed of installation and are a particu-
larly cost effective option for mine and plants operating in Africa,”
Moss says.
The custom engineered sub-station comprises a medium volt-
age (MV) WEG Variable Speed Drive (VSD) and a dry type phase
shift transformer driving a 2 000 kW, 6 pole, 6,6 kV squirrel cage
WEG electric motor. The VSD is housed in the container while the
oil cooled transformer is housed outside of it to facilitate heat dis-
sipation. Moss says that Shaw Controls has an established reputa-
tion for engineering and manufacturing quality bespoke container-
ised solutions at its Johannesburg facility. The extensive facility of
over 12 000 m2 is manned by a team of skilled technical personnel
and having the whole construction take place in one facility makes
it easier for customers to do all quality and functional checks in one
place. This solution underwent testing at Shaw Controls prior to
being dispatched to site.
“What is particularly interesting about the solution provided is
that it has been specifically engineered for this particular applica-
tion and utilises specialised software for frozen charge protection,”
Moss says.
The software, which interfaces with the VSD, allows the objec-
tive detection of a frozen charge condition by making use of torque
measurements already being monitored by the VSD.
“With the addition of an encoder fitted to the electric motor, we
are now able to monitor mill angle. And with the torque and angle
measurements it is possible to detect if cascading has occurred
within the mill,” he explains.
Another innovative feature of this solution is the supply of a Hu-
man Machine Interface (HMI) in the form of an interactive touch
screen which has been configured to allow different levels of ac-
cess. This has been done in a user friendly manner to ensure ease
of use and also allow simple access to relevant data.
Moss says that the ability to extract the most relevant data and
provide this in an intuitive and simplified format allows both oper-
ational and service personnel to monitor the requisite parameters.
This project made use of a WEG MVW01 VSD with 6,6 kV out-
put. The input solution makes use of a 36 pulse rectifier and cor-
responding phase shift transformer. Moss explains that this com-
bination was selected as the best option to minimise harmonics.
Being part of the Zest WEG Group also allows Shaw Controls
access to the substantial technical database and engineering re-
sources of parent company WEG Brazil.
Enquiries: Kirsten Larkan.Tel. +27 (0) 11 723 6000 or email
or visit
Dual-voltage voltage transformer being developed
A move by several major metropolitan mu-
nicipalities, among others, towards raising
the transmission voltage for substations
from 88 kV to 132 kV has prompted AC-
TOM High Voltage Equipment to develop
a dual-voltage voltage transformer (VT) to
facilitate the transition at minimal cost to
users.
“The conversions due to be implement-
ed by various electrical authorities will in-
volve a process whereby substations that
are to be converted need to operate at 88
kV for a period until the conversion to the
higher voltage level of 132 kV has been
completed,” explained Etienne Venter, the
division’s Design Engineer.
“Consequently if an 88 kV substation
is to be converted into a 132 kV facility, it
requires replacing the existing 88 kV VTs
with 132 kV units. We have overcome
this stumbling block by developing the
new dual-voltage VT, which provides for a
seamless changeover from the lower to
the higher voltage without the customer
having to incur the extra cost of replacing
existing units with higher rated ones.”
Design of the new VT commenced late
last year. “What enabled us to develop it
as speedily as we have is that the bulk of
the design was based on the already prov-
en design of the 132 kV compact VT we
developed and introduced into the market
in 2015,” said Venter.
Enquiries: Casbah Zwane.Tel.
+27 (0) 11 820 5369 or email
TRANSFORMERS + SUBSTATIONS
Kirk Moss, medium voltage manager at Shaw Controls, in front of the
containerised solution that will supply power to drive a mill on a mine in Mali.
Etienne Venter, ACTOM High
Voltage Equipment’s Design
Engineer, and (from left)
Andries Modime, Assistant
HV Tester; Clarence Tsire,
HV Tester; and Silas Risimati,
Team Leader, VT Winding
Section, with the prototype of
the new dual-voltage VT now
in production.