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New Efficiency Standards for Motors

First published in the October 2015 issue of Quarry Management as Raising the Standard

Meeting the new efficiency standards for power drive systems. Yasar Yüce, product manager at Bauer Gear Motor, looks at the reasoning for the new EN50598 standards as well as the implications for manufacturers and end-users

Improving the efficiency of electric motors has been an ongoing objective around the world, with several standards now in place to help achieve this goal. It is generally recognized, however, that a broader view is needed to fully maximize 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.

On 1 January 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 7.5kW and 375kW must use either an IE3 rated motor or an IE2 motor installed with a variable-frequency drive (VFD). This approach is focused 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). Essentially, this 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. 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 eco-design 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 will not be forced to provide the losses data at the specified part load.

For transparency, Bauer will be publishing the necessary data both in paper format and on their website. This is in contrast to many manufacturers of complete power drive systems who, according to Bauer, will probably only provide the IES rating of their equipment rather than the losses data relating to the individual components. Potentially, this could leave a customer with a very efficient drive module that was connected to a considerably less-efficient electric motor. Bauer customers will have clarity of the loss data according to EN 50598 for all components, allowing them to calculate the total losses and, as currently, optimize their system.

Having started work on compliance with this new regulation shortly after the proposal was announced in 2010, Bauer believe they are one step ahead in terms of design and efficiency with their complete range of IE3 motors already in the marketplace, including all those between 0.75kW and 7.5kW which meet the regulations due to come into force in January 2017. All of the motors manufactured by Bauer are at least IES1 ready.

The company has also optimized its motors for use with inverters with both permanent magnet synchronous motors (PMSM) and asynchronous motors (ASM) having a 70Hz 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.

In order that customers have a better understanding of the latest standards and how Bauer’s products conform, the company has published the IES classes applicable to its IE2 and IE3 motors, in accordance with EN 50598-2, on its website along with details of the efficiency ratings of its inverter-rated motors. Customers will, therefore, be able to specify the most appropriate components for each application and optimize the energy savings at the same time.

The improvements in energy efficiency that can be gained through careful product selection will benefit not only end-users but also original equipment manufacturers (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.

An OEM will, therefore, be able to promote improved efficiency for its equipment while also reducing the costs of many of the components. Furthermore, 30% greater energy savings can be achieved by use of Bauer PMSMs 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 a 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 are looking to optimize their energy expenditure as part of a drive to reduce operating costs.

While the minimum energy-efficiency ratings are tightened for the majority of motors, there are some exceptions – namely brake motors and those operating in potentially explosive atmospheres – that will retain their exempt status. Once again, Bauer claim to be leading the field in this area with the development of their S series of PMSM, which offers variable-speed motors in efficiency class IE4 for use in explosion hazardous areas.

Bauer welcome the new standard and believe it will provide end-users with a far more accurate picture of the potential energy savings available from complete drive systems, rather than just the electric motor. It will also deliver a better understanding of life-cycle costs for new equipment and its affect on the running costs of a facility.

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