By using the new electrical switchgear, users can be confident that their drive system will achieve maximum energy efficiency levels throughout its long lifespan. Furthermore, the new switchgear reduces the total cost of ownership (TCO) while complying with current environmental protection regulations.
According to European Regulation 640/2009/EC, which came into force last January, motors with a rated power of 7.5 kW to 375 kW sold in Europe must comply with at least the IE3 energy efficiency standard, or IE2 if equipped with a variable speed drive. To meet this challenge, motor manufacturers had to redesign their motors, using more copper in the stator, developing thinner silicon steel laminations in the iron cores, optimizing air gaps, using longer conductors in the rotors, and improving cooling systems. These changes make IE3 motors more inductive, meaning they typically have lower rated operating currents and higher starting currents compared to IE2 motors. In comparative tests of IE3 and IE2 motors with the same rated power, WEG demonstrated that, in the lower power range, the starting current and maximum connection current of an IE3 motor are, respectively, around 5% and 20% higher than those of an IE2 motor.
These tests also revealed that WEG's RW series (bimetallic) and new RW_E series (electronic) motor protection relays are unaffected by the higher starting and connecting currents of IE3 motors. Furthermore, WEG has updated its CWM, CWC, and CWB contactor series to accommodate higher starting and connecting currents without adverse effects on mechanical or electrical lifespan.
Of all motor protection devices, motor starters are particularly vulnerable to the higher starting currents of premium efficiency motors due to their high sensitivity. Therefore, WEG has increased the tripping threshold of its MPW series of motor starters from 12 to 13 times the maximum rated operating current to ensure compliance with the IE3 standard. Regarding the further development of energy-efficient motors, WEG will offer its customers contactors and motor starters that conform to the IE standards.
