Electricity + Control August 2017

round up

TRANSFORMERS + SUBSTATIONS

Containerised electrical solution to drive mill on mine in Mali

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 marketing@zestweg.com or visit www.zestweg.com 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.

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 m 2 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.

Dual-voltage voltage transformer being developed

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.

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.”

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

Enquiries: Casbah Zwane.Tel. +27 (0) 11 820 5369 or email casbah.zwane@actom.co.za

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.

Electricity + Control

AUGUST 2017

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