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Meeting EN50598 efficiency standard for power drive systems

Yasar Yüce of Bauer Gears looks at the reasoning for the new EN50598 standard and the implications for manufacturers and end users.

Improving the efficiency of electric motors has been an on-going objective across the world, with several standards now in place to help achieve this goal. However, it is generally recognised that a broader view is needed to fully maximise the efficiency of the entire drive train. This requires engineers to take account of the efficiencies of the starter systems, as well as the equipment attached to the motor; which has led to the introduction of a new standard, EN50598.

From January 1st 2015 the latest efficiency regulations for electric motors came into force in Europe under Regulation 640/2009, whereby any new installation using a motor between 7.5 kW and 375 kW must use either an IE3 rated motor or an IE2 motor installed with a variable frequency drive (VFD). This approach is focussed on improving the efficiency of a specific product and reducing the losses associated with it alone.

Specifiers and end users need to decide which option as a combination will provide the most efficient solution for their application; an IE3 motor has a clearly specified efficiency rating at its rated speed and at 50%, 75% and 100% load. An application which requires variable speed adjustments and different loadings cannot be evaluated at present with the available product performance data. A specifier or an end user is currently unable to compare the different competitive components of the drive system and finally choose the most efficient motor and inverter components.

A similar situation arises when the motor is integrated into a product, such as a fan or a pump, where the motor's performance cannot be measured independently from the product. In order to address these situations and to improve the potential energy savings in these areas, a new standard, EN50598, is being developed which benchmarks the efficiency ratings of power drive systems (PDS).

EN50598-1, sets out the general requirements for setting energy efficiency standards for power driven equipment using the extended product approach (EPA), and semi analytic model (SAM). This essentially covers the combined efficiency ratings for the PDS and the driven equipment such as the pump, gearbox, compressor etc.

EN50598-2, will widen the focus from a single component to the efficiency of the complete power drive system (PDS). The new efficiency classes (IES) provide a structure that allows the losses for a complete drive system to be compared. The median range is IES1, and systems with losses 20% higher than that of IES1 are classed as IES0. More efficient systems, with energy losses 20% below IES1, are identified as IES2.

EN50598-3, provides a quantitative ecodesign approach through life cycle assessment, including product category rules and the content of environmental declarations.

This new standard will also help end users to gauge payback periods more accurately. Previously, the overall efficiency of speed controlled motors was estimated using rough energy consumption figures. Now, with verified efficiency curves, the payback period for a motor/drive combination can be calculated more realistically.

For manufacturers of variable speed drives there will be a requirement to provide losses data according to the part load measurement points as defined for the CDM system, while those producing motors or gear motors are not to be forced to provide the losses data at the specified part load. However, Bauer wishes to be transparent about the efficiency of its products and will be publishing the necessary data both in paper format and on its website.

All of the motors manufactured by Bauer are at least IES1 ready and its experienced engineers can provide expert assistance to end users and specifiers in the most appropriate equip-ment selection.

Bauer has also optimised its motors for use with inverters with both permanent magnet synchronous motors (PMSM) and asynchronous motors (ASM) having a 70 Hz curve which allows these products to achieve an IES2 efficiency classification in combination with the Reference CDM for the power drive system under EN50598-2.

With the technology already in place, Bauer is contributing to improved energy efficiency and delivering plant and application optimisation. In order to enable customers to have a better understanding of the latest standards and how the Bauer products conform, it will be publishing the IES classes applicable to its IE2 & IE3 motors, in accordance with EN 50598-2.

In this way customers will be able to ensure that they can specify the most appropriate components for each application and optimise the energy savings at the same time. Further assistance in this process will also be available from a team of experienced engineers that will offer expert advice on product selection.

The improvements in energy efficiency that can be gained through careful product selection will benefit not only end users but also OEMs. For many applications a smaller Permanent Magnet Synchronous Motor can be used in place of a larger Asynchronous motor, allowing smaller components to be selected through the complete energy chain.

The OEM is able to promote improved efficiency for its equipment while also reducing the costs of many of the components. Furthermore, 30% higher energy savings can be reached by use of the Bauer Permanent Magnet Synchronous Motors in comparison with asynchronous motor technology operating in standard applications under partial load conditions. The cumulative effect of the energy savings across a number of applications will reduce the total electrical demand for the premises, which in turn will reduce the operating costs of the whole site for the end user.

The changes that are being implemented by manufacturers will have a direct benefit to end users, especially those in industries that employ electric motors in continuous operations. For example, many applications in bulk materials handling, the food and beverage sector and metal processing as well as those in the automotive and logistics sectors are looking at optimising their energy expenditure. Similarly, water treatment and chemical processing plants will be able to identify the most efficient drive systems as part of their drive to reduce operating costs.