WEG's new MVW-01 range of medium-voltage drives is said to be setting new benchmarks for medium-voltage (MV) drive efficiency, achieving 99 per cent with a new design that employs Multilevel Topology to minimise component levels, and high-voltage (6.5kV) IBGTs to reduce motor harmonic currents to extremely low levels.
WEG says that the introduction of the MVW-01 drives makes it the only supplier of speed variation systems for medium voltages that can offer a 'total package', including input switchgear, dry or oil-filled phase-shifting transformer, variable-speed drive (VSD) and medium-voltage motor.
Unlike many MV drives on the market, which have three- or five-layer control, the WEG MVW-01 range has just two layers. The benefit of this is a reduction in the number of components in the drive and commensurate improvements in efficiency and reliability. With energy costs now very high, the efficiency performance of the MVW-01 drives is all- important. It has been calculated that for every 1 per cent of efficiency lost on a 1MW drive, the user will pay an extra EUR7380 (£5000) per year on running costs - and that figure is just for the drive alone.
The MVW-01 drives are voltage source inverters (VSI) employing the latest multi-processor control architecture. They integrate a 32-bit high-performance processor (64-bit bus) with floating-point capability to provide high-performance control of MV motors in the voltage range from 2.3 to 4.16kV and in the power range up to 3355kW. The MVW-01 drives are an excellent complement to WEG's H line of MV motors, which cater for outputs to 3150kW and voltages up to 6600V (50 or 60Hz). Like the MVW-01 drives, the H line motors are compact and extremely robust machines, suitable for operating conditions encountered in the most arduous industrial applications.
Housed in compact IP41/NEMA 1 enclosures, the MVW-01 drives offer users the convenience and cost-saving benefits of air cooling. They are configured for 12-pulse operation, with 18-pulse available upon request. These ensure excellent voltage waveforms for the drives, and result in a high power factor (< 0.95) that fully meets the requirements of G5/4 and IEEE-519.
The MVW-01 drives deliver high levels of reliability and low noise levels (<75dBa) with a design that offers a number of key features: it includes the latest generation of high-voltage (6.5kV) IBGTs; provides optical isolation between the control section and the high-voltage sections of the drives; and employs ultra-reliable dry-type plastic film power capacitors. In addition, the design also includes removable power arms for fast and simple maintenance.
Contradicting the commonly held belief that MV drives are difficult to use, the MVW-01 units follow the same simplified programming structure as WEG's LV drives. They are equipped with a smart keypad with dual LCD and LED displays. The keypad is language selectable and offers users complete flexibility, providing programming and intelligent operator interface facilities. In addition, the drives can be programmed on- or off-line using a PC.
Andrew Stevens, WEG product manager, comments: We think that the launch of MVW-01 drives is set to change the way engineers think about MV drives. In the pastcontrol engineers would veer away from MV drives because of their cost and complexityand employ LV systems working at high currents.
Howeverthe problem with using LV drives at high power is that cable and installation costs are high. In additionLV installations require shielded EMC cablewhich is very expensive. MV driveswhilst usually costing more as a proprietary itemavoid these expensesdue largely to the lower current their cables carry and the fact that they do not need to employ expensive EMC shielded cables."
For more informationvisit www.weg.com.br
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