Electricity + Control February 2019

TRANSFORMERS + SUBSTATIONS

Applying its integrated solutions approach at Cullinan Mine’s new diamond process- ing plant last year, the Zest WEG Group has demonstrated a range of its capabilities in the upgrade of what is now a much more sophisticated and efficient facility. Integrated electrical make-over for Cullinan's diamond processing plant

Take Note! While consuming less power and water, the new plant will minimise the risk of damage to large diamonds. Key to these achieve- ments is the design and installation of state-of- the-art electrical and con- trol systems.

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A s part of the plan to extend the life of Cullinan Mine near Pretoria by 12 years, owners Petra Diamonds have significantly revamped the processing side of the operation to deliver higher performance on a smaller footprint. While consuming less power and water, the new plant will also minimise the risk of damage to large diamonds recovered from the Cullinan ore- body and improve the recovery of low luminescent Type II white and blue stones. Key to these achievements has been the de- sign and installation of state-of-the art electrical and control systems by Zest WEG Group’s Inte- grated Solutions division, with the input of oth- er companies within the Group including WEG Transformers Africa, Shaw Controls and EnI Elec- trical. According to Alastair Gerrard, Zest WEG Group’s Integrated Solutions Executive, the pro- ject was a prestigious contract for the Group. “Our diverse product and solutions package al- lowed us to provide a comprehensive solution to Petra,” says Gerrard. “Close collaboration and con- tinuous interaction between all the parties were key to the success of the project.” The scope of this work included the 60 MVA 88/6,6 kV bulk substation, dedicated to the Cull- inan Diamond Mine, as well as an 88 kV switch- ing station. The switching station was provided on a ‘self-build’ basis, built and funded by Petra Diamonds while remaining in the ownership of Eskom. With the Zest WEG Group conducting the

procurement, construction, erection and commis- sioning, they were required to work closely with Eskom for the duration of the work. In terms of the supply of transformers, 26 units were provided by WEG Transformers Africa, rang- ing in size from 100 kVA to 20 MVA, over a voltage range from 88 kV to 380 V. With manufacturing facilities in Wadeville and Heidelberg in Gauteng, WEG Transformers Africa is considered one of the largest manufacturers of mini substations and dis- tribution transformers in South Africa. A range of equipment was supplied by Zest WEG Group company Shaw Controls, which has over three decades of experience manufacturing motor control centres (MCCs), distribution boards, medium voltage (MV) switchgear, control desks, PLC and instrumentation enclosures, portable and containerised substations, E-Houses and various other electrical enclosures. For the Cullinan project, Shaw Controls sup- plied six 525 V, 50 kA MCCs; two medium voltage 6,4 MW, 3,3 kV MV mill drive packages, each com- prising a variable speed drive (VSD), motor and transformer; two 1 MW low voltage VSDs; 170 field isolator stations of 525 V; and two container- ised 525 V substations. Zest WEG Group company EnI Electrical – which constructs specialist electrical, instrumenta- tion and control systems – also played a key role in the project. Its contribution included the construc- tion of the 88 kV lines from the Eskom self-build switching station to the Cullinan bulk substation,

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Containerised 525 V substations manufactured by Shaw Controls and installed at the New Dam 7 pump station at Cullinan.

30 Electricity + Control

FEBRUARY 2019