efficiency determination and classification,” can be a key resource. Instead of focusing solely on motor efficiency, it details a series of higher-level performance factors for “electric motor-driven systems.” VFDs are considered in the context of a complete drive module (CDM) that includes the AC input ‘” feeding section,” a “basic drive module” (BDM) like a VFD, and “auxiliaries” that include input and output filters, line chokes, and other support components. The standard also defines a power drive system (PDS) as the CDM plus the motor. Next up the hierarchy, the standard describes the motor system as the PDS plus motor control equipment like contactors. At the highest level is the extended product, or overall system in Figure 1, which adds mechanical drive equipment like a transmission and the load machine. For a more detailed review of IEC 61800-9-2 PDS efficiency standards, check out the article “What are the different types of adjustable speed industrial motor drives?” The starting point for specifying “electric motor-driven systems” is the motor.
specified and used. That makes specifying motors an important task for machine designers. The IEC quantifies motor power in kilowatts (kW), while NEMA uses horsepower (hp), which can be easily equated. However, IEC and NEMA use different efficiency calculations, and IEC nameplate efficiency can be slightly higher than the NEMA rating for the same motor design. Actual motor efficiency is strongly tied to the specific use case. As a result, motor efficiency standards
are often discussed in terms of reductions in energy losses rather than absolute efficiency. IEC 60034-30-1 recognizes five motor efficiency classes, from IE1 to IE5. Energy losses decline 20% between classes. That means an IE5 “Ultra Premium” motor has 20% lower losses than an IE4 “Super Premium” motor. There’s more to consider. In some cases, the power factor (PF) declines for motors with higher efficiency. In North America, NEMA has fewer energy efficiency classes,
Motor matters Electric motors can be highly efficient machines if properly
we get technical
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