LEXINGTON, TN — At the recent ASHRAE 2001 Winter Meeting, a forum focusing on the utilization of high-efficiency electric motors and their potential impact on overall system characteristics was conducted. Participants explored the suggestion that higher transformer losses might well offset the energy savings of the motor, primarily due to lower system power factors. As is most often the case, there is no substitute for an informed buying decision, and that applies to electric motors as well.
High efficiency in an electric motor does not necessarily equate to low power factor. It is true, however, that the use of lower loss electrical-grade steels, larger operating air gaps, and the tendency toward as much locked rotor (inrush) current as possible do dominate motor design decisions at the potential sacrifice of power factor. The designer can compensate for these tendencies through the use of more active material in the motor, achieving power factors at or near Pre-EPAct 92 levels.