The WEG MVW3000 VSD is a new addition to WEG Automation Africa's medium voltage (MV) VSD portfolio. The units placed in West Africa are the first two that it has produced and will be used to support 850kW ventilation fan motors.

The design of the newly unveiled VSD is based on cascaded H-bridge (CHB) topology, which utilises multiple low-voltage power cells in combination to achieve desired voltage output. The input switch, phase-shifting transformer and VSD are fully integrated within a single MV panel.

One benefit is its ability to give high-quality input power using low harmonic multi-pulse transformers; users benefit, officials said, from a high efficiency of over 96.5% throughout the entire load range. In addition, throughout the speed range, it can realise a power factor of more than 0.95.

"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," WEG Automation projects and engineering senior manager Kirk Moss said.

"The design includes power cells with long-life plastic capacitors, which are more reliable and last longer than dry type capacitors. They also have the advantage of not needing to be reformed after long periods of storage."

The 11 kV VSD is available from 40A to 400A - or 640kW to 6,500kW - in standard configurations. WEG noted that larger sizes are available if required. It also can be ordered with options, such as the WEG MVW3000 automatic cell bypass solution.

"This ensures minimal reduction in the output-rated torque so that normal operations can continue. Redundant power cells can also be added to the design to ensure that 100% torque can be maintained. Prior to delivery, all VSDs are fully load-tested in WEG's state-of-the-art facility in Brazil," the company said.

WEG Automation Africa is part of the Zest WEG Group.