Efficiency as standard

Paul Boughton

Heikki Kervinen explains what the new energy efficiency standards mean and how you can benefit from them

Energy efficiency in industrial manufacturing is currently a hot topic as the new EN50598-2 standard published in December 2014 has put it firmly in the spotlight. The goal is to get further efficiency and energy savings, with the standard introducing new IE classifications for total efficiencies in the complete drive module (CDM) and the power drive system (PDS). Presently the IE classification applies only to motors, but the new standard will take a broader approach for complete variable speed drives (VSD) and motor packages.

This is not without reason. Motors consume an astonishing 28% of the world’s electricity and most pump and fan applications are oversized to err on the side of caution in meeting a system’s maximum demand. Variable torque applications often obey the cube law, which means power demand increases to the third power of the speed. Therefore a small increase in speed requires a lot more power but, conversely, a modest speed reduction can mean big energy savings. Modern intelligent motor control methods such as variable speed drives can play a key role in increasing energy efficiency, with substantial financial and environmental benefits.

As a major manufacturer of both motors and drives and therefore total power drive systems, ABB strongly supports the new standard because it is very much aligned with its existing philosophy. With proper application, EN50598-2 will help OEMs and industrial users to get better operational efficiencies in complete systems, not just individual components.

However, if at this point you are a bit confused by the new standard and the IE classifications it includes, don’t worry: you are not alone. The standard is not entirely easy to understand but this article will help explain it and also describe how ABB’s expertise can help gain clear and valid comparisons of total efficiency.

The short explanation of EN50598-2
The EN50598-2 standard defines new IE classes for the complete drive module (CDM) and new IES classes for the power drive system (PDS). It applies to motors and drives with a voltage range of 100 to 1000V, and a power range up to 1000kW.

As you may know, direct-on-line (DOL) motors that are connected directly to the electrical supply without any drive have had IE classifications of IE0, IE1, IE2, IE3 and IE4 for several years. The higher the number, the better the efficiency is.

The new EN50598 standard introduces the new term CDM (for complete drive module), which is in practice the same as the old term VSD (variable speed drive). CDM now has IE classes IE0, IE1 and IE2 but, it is important to note, these IE classes are defined differently from those for DOL motors.

The new EN50598 also for the first time defines the term PDS (power drive system), which equals the total system efficiency even accounting for losses. So the PDS is the motor + VSD combination and is rated with new IES classes IES0, IES1 and IES2 where the S stands for system.

Like a pump curve for the system
Generally, industrial process operators already know the conditions and the operational points at which they are running. Equipped with this process knowledge, and better data for combined drive-motor power efficiency that the new standard will produce, it is easier to evaluate efficiency and power losses. For example in a pumping application, by knowing the operating ranges, engineers can more accurately calculate losses in the entire motor-drive-pump system. This is somewhat analogous to a pump curve where a specific piece of equipment’s performance is well defined, except that it is now combined motor-drive-pump data. This offers a much more accurate indication of what the efficiency of the system will be, instead of using assumptions of how the various components will interact.

Now customers will have this data clearly documented under standard EN50598-2. This will support both OEMs and industrial operations for their classification and reporting requirements. It will also help in prioritising where energy-saving investments should go, to improve ROI of the operation. Since ABB makes both variable speed drives as well as motors, it can calculate and verify the IES values for the entire system.
Today’s intelligent VSDs play a critical role in these systems by monitoring, optimising and reporting on energy consumption and making sure the very minimum energy is used to run the motor. ABB’s new ACS580 general purpose drive is very well adapted to both save energy and meet the reporting requirements of the new standard. It fulfils the highest IE2 drive energy efficiency class and includes advanced energy efficiency analysers and energy optimiser controls. For compatibility, the drive supports energy efficient motor types including high-efficiency IE4 motors such as induction, asynchronous and permanent magnet motors provided by ABB.

There are numerous smart functions built into the drive. For example, the energy optimiser features ensure maximum torque per ampere in both scalar and vector control modes, reducing energy drawn from the supply, and providing additional energy savings up to 10% in partial loads. It is also easy to generate accurate reports on hourly and daily energy consumption, as well as the cumulative information. 

For both financial as well as environmental audits, if earlier direct on line (DOL) power consumption data is given as a benchmark, the drive can calculate the monetary savings and reduced CO2 emissions. The data generated also makes it easy to estimate the ROI of the power drive.

Achieving superior energy efficiency is a job that is never really finished and ABB’s life cycle services are set up to ensure processes run efficiently year after year. This means complete services are offered, from dimensioning and commissioning, through to eventual replacement with a more efficient drive at the end of the life cycle. The result is continuous efficiency improvements and savings in both energy and operational costs.

ABB’s ACS580 drive is highly suited to help customers meet the new EN50598-2 standards. For the CDM it has the highest IE2 class rating, which means the best efficiency. Data is also available giving losses/efficiency at several operation points as defined in EN-50598-2.

For the new IES classifications for PDS, since ABB makes both motors and drives it can provide OEMs and users with verified values for the range of operational points according to EN-50598-2.

In addition to saving energy, the abovementioned benefits will support customers’ classification and reporting requirements, and also help in prioritising where energy-saving investments should go for improved ROI of the entire operation.

For more information visit www.engineerlive.com/ede

Heikki Kervinen is with ABB in Finland.

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