For signatories to the Kyoto Protocol, 2012 is a year of great importance. It’s when parties to the legally binding protocol report on their efforts, in respect of lowering the overall emissions from six greenhouse gases – carbon dioxide, methane, nitrous oxide, sulphur hexafluoride, HFCs, and PFCs – calculated as an average over the five year period of 2008-12.
The Kyoto Protocol is flawed of course, the US is not a signatory, and Canada withdrew in 2011, but it has proved to be a call to action across many energy intensive market sectors. What all these sectors have in common is their use of electric motors, which are the single biggest consumer of electricity worldwide. They account for about two thirds of industrial power consumption and about 45% of global power consumption, according to a new analysis by the International Energy Agency.
Unsurprisingly, In view of these figures, electric motors have been one of the main target areas for improving energy efficiency. The resulting efforts in this area have generated new energy efficient standards, such as the latest IEC 60034-30:2009, a harmonised IE (International Efficiency) grading standard, which is central to the EU’s new eco-design directive 2005/32/EC.
Many manufacturers have anticipated the new standard, and have produced energy efficient products to comply. But is this enough, bearing in mind that every standard is a compromise, in the final analysis? One company, WEG thinks not, and has exceeded the requirements of standards in its latest motor and drive designs – both LV and MV.
The first evidence of this approach is WEG’s new WQuattro line of super premium efficiency motors. These employ a hybrid design to achieve the highest efficiency in the market, exceeding the requirements of the impending IE4 Super Premium Efficiency classification across their entire output range.
The WQuattro line has been developed for users who consider energy saving a major priority. It is an environmentally friendly range of motors that, due to its efficient performance – with no energy (joule) losses from its rotor – demands less energy from the grid. For the user, this translates into lower total cost of ownership, a reduction in CO2 emissions, and a faster return on investment.
The WQuattro is a hybrid motor integrating a conventional 3-phase distributed winding, and a rotor with an aluminium cage and internal high energy magnets. This combination makes the WQuattro well suited for direct online starting and acceleration up to synchronous speed. With this type of operation the motor speed does not vary with load, despite overload variations, or cases of voltage drop, as long as the mains frequency is kept constant. Moreover, there is no requirement for positioning/speed sensors, or special protection relays, and the low bearing temperatures that result from synchronous operation also ensure longer life and reduced maintenance for the motors.
In addition to developing energy efficient motors for general industrial and process applications, WEG has also focussed its design efforts on improving the efficiency of more specialist designs, such as permanent magnet (PM) motors. This technology has tended to be very much on the back burner, due to the design of standard squirrel cage motors, which are relatively inexpensive, robust and reliable, and well proven in operation.
WEG’s new WMagnet series of PM motors, changes this situation by offering a range of user benefits that bring PM motors into mainstream usage. The WMagnet series delivers higher efficiencies – up to 97.5% – compared to equivalent size induction motors, and reduces size by up to 50% and weight by up to 36%. In addition, the motors are, generally, at least one frame size or core length smaller than the equivalent induction motor, and in some cases can be two frame sizes smaller.
The energy efficiency of WEG’s PM design has been demonstrated in one of the prototype applications for the motors, at a textile mill. By replacing standard induction motors used on ring spinning machines with permanent WMagnet motors, the textile plant has reduced its annual power consumption by a massive 33% and increased its machine utilisation by 80%.
Both the WQuattro and WMagnet are low voltage motors, however, a substantial section of the motor market is MV, and here too, the potential for energy efficiency is considerable. WEG is exploiting this potential with its new MV drive, the MVW-01, which achieves 99% efficiency with a design that employs Multi-level Topology to minimise component levels, and high voltage (6.5kV) IBGTs to reduce motor harmonic currents to extremely low levels. With energy costs at record levels, the efficiency performance of the MVW-01 drives is all important. It has been calculated that for every one percent of efficiency lost on 1MW drives, the user will pay an extra £5,000 per year on running costs – and that figure is just for the drive alone.