IE3/IE4 motors can achieve higher efficiency thanks to innovative design and the use of better conducting material. The higher efficiency design ultimately shows a lower rated motor current for any given kW rating. However, during the motor’s starting phase, there may be an increase in inrush and starting current. The increased inrush and starting current can in some cases affect the selection of the starter components as well as the short-circuit protection device.
The new utilization category AC-3e is a category of electrical switching devices designed for operating premium-efficiency motors. The AC-3e category was specifically developed to meet the latest requirements for IE3 and IE4 premium-efficiency motor applications. The AC-3e category is an extension of the AC-3 category and provides higher performance than the AC-3 category. The AC-3e category is an important advancement in energy efficiency and helps reduce energy demand.
ABB has validated coordination solutions for AC-3 and AC-3e direct online (DOL) applications. The results of these tests can be found in ABB’s motor coordination tables and in the ABB’s Selected Optimized Coordination tool (SOC)
For a deeper look into the technical background of switching high-efficiency motors, we recommend our application note:
PDF - Motor starting and protection for premium-efficiency motors (abb.com)