Energy efficient electric motors some caveats to their use

The injudicious and automatic replacement of standard motors with IE2 and IE3 motors can have potentially serious, unwanted and unintentional side effects. If one does not make allowances for these in the system design, a 1% improvement in energy efficiency on the motor alone may well result in an actual increase in the overall system energy consumption. The main message of this paper is that when one looks at optimising energy conservation and efficiency one should never look at only the specific efficiency of a single item of a system, (e.g. the electric motor as is usually the case) but always at the efficiency, and energy consumption, of the entire system. The electric machine/motor discussed in this paper refers to AC induction machines.