Motors for use in explosion hazardous areas are exempt from the EU regulations on minimum energy efficiency because, clearly, explosion protection takes precedence over energy savings. This has put some industries, such as Oil and Gas and Mining, at a disadvantage when trying to improve the overall efficiency of their operations. While safety has to be prioritised in such environments, historically this exemption has meant that operators are missing out on potential energy savings of as much as 40 percent.
Fortunately Bauer Gear Motor, part of Altra Industrial Motion, has a long history of working within such sectors and has developed the S Series of Ex rated IE4 motors. The launch of the S Series means that applications which require motors to be specified and designed to meet ATEX classifications can now benefit from similar energy savings as found in other industrial areas.
Currently most Ex e (Increased Safety) rated variable speed three-phase induction motors on the market are generally available in standard efficiency class IE1. While the efficiency of these can be improved with the addition of frequency inverters, they still fall well short in comparison to the improved design of IE3. IE4 motors are now implemented in the IEC standard IEC 60034-30 Edition 2 draft, in addition to the newly included IE efficiency level classified for variable speed motors. The S Series offers the best of both worlds; Ex e rating with the potential to achieve energy savings of up to 40 percent compared to an IE2 inverter- driven squirrel cage motor.
The S series is part of Bauer's PMSM motor range which has been proven to provide the best possible energy efficiency. The range of motors are available from 0.55kW to 15kW and are classified for Zones 1 and 21. Not only are they superior at converting electrical energy into mechanical power, they also offer the added benefit of maintaining constant speed independent of the load. This means that motor speed does not vary, despite overload variations, or cases of voltage drop, as long as the mains frequency is kept constant.
PMSM synchronous motors offer considerably improved efficiency when compared to induction motors even under partial load conditions; and extremely high efficiency under rated operating conditions. They also have considerably higher power density, which, for geared motors, yields higher system efficiency with minimal installation volume – and also reduced weight. Importantly PMSM drives can produce higher torque values for the same installation volume as conventional induction motors, a factor that allows cost saving, through the ability to specify a smaller motor size in some applications.