What are some key considerations when selecting industrial automation equipment?
Figure 2: Comparison of NEMA and IEC industrial AC voltage and frequency ranges. (Image source: NEMA)
which are just as important. NEMA recognizes motor service factors (SF) not included in IEC standards. A NEMA motor with an SF of 1.15 can be run continuously at 115% of its rated capacity, albeit the motor runs hotter, which can result in reduced bearing and insulation life. Instead of SF, IEC recognizes ten duty types or service factors (S1 to S10) based on considerations like continuous versus
intermittent operation, speed variations, and the use of braking. Operating voltage and frequency ranges differ for NEMA and IEC, but both are expressed as “per unit” (p.u.) quantities. In the p.u. system, quantities are expressed as fractions of the base value. NEMA recognizes one range of motor voltages and frequencies. IEC recognizes two “Zones” (Figure 2).
Driving for PDS efficiency Motor drives are key elements of PDS efficiency as defined in IEC 61800-9-2. They can be classified in several ways, such as motor voltage, power level, motion types, supported applications, etc. Motion types can be classified as continuous or discontinuous. They can be further categorized as low,
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