Two units of the newly developed WEG 11 kV Variable Speed Drive (VSD) have been commissioned at an underground gold mine in Ghana by WEG Automation Africa, a member of the Zest WEG Group, the company says.
According to Kirk Moss, Senior Manager: Projects and Engineering at WEG Automation Africa, the new WEG MVW3000 VSD is a valuable addition to its medium voltage VSD portfolio, and brings a range of benefits to customers.
“It gives WEG Automation Africa even greater flexibility in our market offering, further enhancing our capability to provide customised solutions,” he said.
The first two 11 kV units produced are for 850 kW ventilation fan motors in the underground gold mine in Ghana, according to the company.
The design is based on the cascaded H-bridge topology, using multiple low voltage power cells in combination to achieve the desired voltage output, the company said. The input switch, phase-shifting transformer and VSD are fully integrated in a single MV panel.
Moss said: “The WEG MVW3000 is particularly suited to applications where there are standard motors with no special insulation or where existing motors are being modified for VSD control.”
This VSD delivers high quality input power using low harmonic multi-pulse transformers. Users benefit from a high efficiency of over 96.5% throughout the entire load range, and a power factor of more than 0.95 throughout the entire speed range, according to the company.
“The design includes power cells with long-life plastic capacitors, which are more reliable and last longer than dry type capacitors,” Moss says. “They also have the advantage of not needing to be reformed after long periods of storage.”
In standard configuration, the 11 kV VSD is available from 40 A to 400 A – or 640 kW to 6,500 kW – although larger sizes are also available if required, the company said.
Among the options on the WEG MVW3000 is an automatic cell bypass solution. This ensures minimal reduction in the output-rated torque so normal operations can continue. Redundant power cells can also be added to the design to ensure 100% torque can be maintained.
Prior to delivery, all VSDs are fully load-tested in WEG’s facility in Brazil.