The motor regulation does not currently apply to motors designed for special applications such as explosion-protected motors. In the process industry where explosion-protected drives are often needed, the consequences of the exemption are generally adverse, as it tends to limit the number of suppliers. Nevertheless, several manufacturers had IE2 and even some IE3 explosion-protected motors on display at Achema (see text box).
Incidentally, if you look at the power/efficiency graph for IE1, IE2 and IE3 motors, you will see that the difference in motor efficiency is greatest in the lower end of the power range. At higher power, the efficiency figures are much more similar. This means that users who switch to a high-efficiency motor will see the biggest benefits in the lower end of the power range.
IE3 and IE4 high-efficiency motors play an important role. They save significant amounts of energy and cost in a short space of time. For most users however, switching from a fixed-speed motor to, for example, a system with frequency converter control is the better solution, as is pointed out in the January 2012 issue of the VEM company newsletter.
“Process-based control using a frequency converter and a state-of-the-art IE2 motor is often significantly more effective than simply using an IE3 or IE4 motor.” The systems run in the optimal operating range. Reduced energy consumption is not the only benefit. The process is more stable and maintenance costs are lower.
* The author is a freelance journalist at PROCESS.