Converter-fed motors are products that are specifically designed to convert electrical power into mechanical power, by rotating a drive shaft at a speed that is directly related to the electrical power supplied to the motor. For the ETL, converter-fed ac motor drives consist of a motor, and a matched, electronic variable speed drive (VSD) that is specifically designed to provide the multi-phase electrical power input needed to operate the motor, and to vary its speed in a controlled manner in response to an external signal. Converter-fed motors are applied throughout industry and commerce in a wide range of ‘general purpose’ and specialist applications.
Line Operated Motors
The line operated ac motors technology covers products that are specifically designed to convert standard three phase electrical power into mechanical power, and to rotate a drive shaft at a fixed speed that is directly related to the frequency of the electrical power supply. Line operated ac motors are used to drive plant and machinery throughout industry and commerce, and a wide range of ‘general purpose’ products are available in internationally agreed, standard designs with different rated power outputs, frame sizes, fixed operating speeds, and energy efficiency ratings. The majority of line operated motors are ac induction motors. However, there are a series of new and more efficient motors entering the market. For example, hybrid permanent magnet motors use built in permanent magnets to reduce rotor losses and increase overall energy efficiency.
Variable Speed Drives
A variable speed drive (VSD), is an electronic device that controls the characteristics of a motor’s electrical supply. Therefore, it is able to control the speed and torque of a motor, achieving a better match with the process requirements of the machine it is driving. For applications where variable control is desirable, slowing down a motor with a VSD can reduce energy use substantially.More information (PDF)