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Motor protection system is 'IE3 ready'

22 March 2015

Eaton has carried out extensive tests on products in its popular motor control range to confirm their suitability for use with the latest IE3 high-efficiency motors.

All DIL-series contactors, as well as PKZ and PKE motor-protection circuit breakers, have now been proved suitable for efficient and reliable control of IE3 motors and have, therefore, been certified as ‘IE3 ready’.

The Energy-related Products (ERP) Directive, which aims to increase the efficiency of energy-consuming products, has made it necessary for motor manufacturers to make changes to their designs. Thicker wire is now used for windings to reduce resistance, laminations are optimised to reduce losses from stray magnetic fields and higher quality steel minimises hysteresis losses. 

These changes mean that high efficiency motors have increased inductance, which leads to larger starting currents. Contactors and motor-protection circuit breakers must be able to cope reliably with these developments.

Eaton has examined this issue in depth, and has carried extensive practical testing. DIL series contactors, for example, have been tested to confirm suitability for use with IE3 motors for DOL starting on public and private supply networks, for star-delta starting, for use with soft starters, such as those in the DS7 range, and with PowerXL variable speed drives.

Eaton has also upgraded the characteristics of its PKZ and PKE motor protection circuit breakers to suit IE3 motors. This was necessary because the starting current provision of 8x normal full load current, as specified in the current edition of EN 60947-4-1, is not sufficient for IE3 motors

Had the protection devices not been upgraded, it would have been possible, in some circumstances, for them to trip even though no fault was present. This could have led to dangerous conditions, such as contactor ‘bounce’ resulting in contact damage or even welding.

To eliminate these risks, and to ensure maximum reliability and safety, Eaton products now allow for starting currents as high as 12x to 15.5x full-load current. It is likely that these high factors will soon become industry standards, as work is currently underway to update EN 60947-4-1 to make provision for IE3 motors.

Eaton supports users in the correct selection, sizing and co-ordination of control gear and switchgear for specific applications by making available software tools that include a configuration tool for motor starter combinations, and CurveSelect, a program for choosing short-circuit and overload protection devices. These tools are available free of charge here

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