Lenze is launching the BlueGreen solutions campaign to help save energy, with the 'blue' element coming from Lenze's logo and corporate image, and the 'green' representing the environment. However, the BlueGreen concept has a deeper meaning for energy saving beyond simple changes. Rather than, for example, change to an energy-efficient electric motor with small but worthwhile savings of two to five per cent, the BlueGreen approach is a holistic one to include the whole machine drive. A typical approach might include energy-saving software for partial loads and the re-use of braking energy. Together, these can often yield energy savings in the order of 20 to 50 per cent.
Almost half the electric energy produced in the UK is used by industry, and electric drives are responsible for around two-thirds of this power consumption. BlueGreen takes a three-pronged approach to evaluating the potential and maximise the possible energy savings, bearing in mind costs and payback times.
The first strategy is to work with machine building customers to use energy intelligently - or rather, to use as little energy as possible. The biggest opportunity in this area is the dimensioning of drives. Too often drives are oversized with safety factors being added 'just in case' they are needed. The result is motors running at partial loads, which has a disastrous effect on running costs; as much as 20 per cent can easily be lost from the running efficiency. Here the BlueGreen approach is for Lenze Engineers to evaluate the requirement properly, using a specialist software tool for complex cases, and dimension the drive so that it runs fully loaded at the optimum efficiency. Where the demand on the motor varies, the answer is to use frequency inverters to match the demand. This can give a swift win, with 50 per cent energy savings if the speed is only reduced by 20 per cent, so payback times are short, maintenance is reduced and personal comfort often increased.
Lenze's second BlueGreen strategy is to convert electric energy with a high degree of efficiency. A starting point is to use high-efficiency motors: the change to using them is gathering momentum, with legislation requiring a minimum of IE2 high efficiency by June 2011. Lenze has IE2 motors available, and a particularly wide range of IE2 geared motors with in-line or right-angle gearboxes. In some cases dimensions change from IE1 standard efficiency motors and, in every case, the electrical characteristics are altered. Catalogue data is available to evaluate the effects of a change. Furthermore, inverters can help with efficient conversion of electrical energy. The new Lenze 8400 motec inverter features VFCeco software that adjusts the magnetisation current of the motor to match the load. This can reduce energy consumption by up to 30 per cent. Lenze has efficient gearboxes too. Helical and planetary gearboxes run at around 95 to 98 per cent efficiency, depending on the gear ratio. Rather than offer a worm gearbox with typical efficiency in the band 50 to 70 per cent, Lenze offers an energy-efficient helical bevel alternative that runs at 94 to 96 per cent. A complete drive package of motor, inverter and gearbox can turn electricity into rotary motion with losses remaining well under 20 per cent.
The third BlueGreen concept is to recover braking energy. Not every machine is suitable for this, but typical cases are hoists, positioning and robotic drives, winding and forming machinery. In the past, unwanted energy was dumped to brake resistors where it was dissipated as heat. Lenze has three alternatives to this waste. Where multiple drives are in use, a simple connection of the DC bus enables the energy to be shared, thereby reducing demand on the mains. Particularly for medium to high power applications, a mains regeneration unit may be appropriate. This is effectively a drive that runs in reverse, turning generated DC current into AC current that is fed back into the mains. The third option is capacitor storage, which is effective for fast-cycling drives.
The Lenze BlueGreen options can be adapted to different types of machine and different user profiles. On the one hand, upgrading from a 11kW IE1 standard efficiency motor to one with IE2 high efficiency might save two per cent, or four per cent by going to IE3 premium efficiency. On the other hand, Lenze BlueGreen know-how can have a much greater effect. Savings of 20 per cent are a conservative estimate and figures of 50 per cent are not unknown.
Follow the link to find out more about Lenze BlueGreen Solutions.