Many people in the local industry are still under the impression that cutting edge VSD technology only comes out of countries like Germany and Japan, but Zest WEG Group’s modular drives can compete with these products at all levels.

The Zest WEG Group has successfully manufactured, delivered, installed and commissioned its first locally manufactured new generation CF11-M modular Variable Speed Drive (VSD). The 750 kW,1 600 A normal duty, 380 V modular VSD was supplied to Weir Minerals Africa, together with three motors — 750 kW, 400 kW and 110 kW — for use within its state-of-the-art in-house pump test facility at Isando.

Modular VSDs were previously assembled into enclosures by Zest WEG Group’s holding company, WEG, in Brazil and imported to the African market as a complete product. However, Zest WEG Group company, Shaw Controls has developed an enclosure to suit the South African market and is able to assemble modular VSDs into locally manufactured enclosures. This makes it possible for the steelwork to be fabricated to local requirements, such as allowing sufficient space for power terminations.

“The addition of locally manufactured CF11-M modular VSDs to our product range has benefited Weir Minerals Africa in terms of a lower cost, custom design and a manufacturing period reduced from 12 to six weeks,” Johan van Niekerk, Zest WEG Group manager for automation, says. “The multi-disciplinary resources within the Zest WEG Group also reduce the risk to the customer who is, in effect, dealing with one organisation and one point of contact.

“Although the VSD technology came from WEG Brazil, the contract was executed locally by Zest WEG Group’s drives and automation specialists, who performed the custom design, testing and commissioning. Shaw Controls manufactured the enclosure and assembled the modular VSD, while EnI Electrical, another Zest WEG Group company, performed the site installation and cabling of the modular VSD to Weir Minerals Africa’s supply and pump test rig.

The Zest WEG Group stocks components for the modular VSD at its Johannesburg warehouse to further reduce the manufacturing period.
WEG Variable Speed Drives
The CFW11 modular VSD incorporates world leading technology for control of three -phase induction motors. The system was developed based on plug-and-play philosophy, allowing simple and fast installation of the VSD and its accessories. The keypad has a navigation and programming system similar to mobile phones, with soft-key buttons.

The CFW11-M modular VSD comprises complete cubicle modules and switchgear assembled in a robust steel enclosure. The main design components are the control unit, rectifier module and power modules (inverter). The modular VSD features the new generation of WEG CFW11 frequency inverters for ratings ranging from 370 kW to 2 000 kW, with line voltages from 380 V to 690 V. The compact power modules can be configured to achieve the required motor power ratings using a combination of up to five power modules.

Full-featured monitoring and protection functions in the VSD help prevent heat build-up for longer motor life and safer, more reliable performance. Its IGBT overload protection feature monitors junction temperature (via thermal imaging) and has built-in protections and alarms. For example, the heat sink fans have an automatic on/off control to ensure added protection.

WEIR MINERALS AFRICA VSD PIC 01 : WEG AFW11M modular VSD connected to a WEG 330 kW motor at Weir Minerals Africa.

WEIR MINERALS AFRICA VSD PIC 02 : A view of the WEG AFW11M modular VSD at Weir Minerals Africa showing the two modules.