Rotating electric machinery and transformer technology

Increasing use is now being made of solid-state motor controls. The vast majority of installed motors continue to use the traditional electromagnetic relays and contactors, but newly-designed installations are turning more and more frequently to solid-state controls. Since the use of diodes, transistors, SCRs, DIACs, and TRIACs has moved from the laboratory to the commercially recognized product, it is necessary that the emerging technician and engineer understand their applications in motor control. The major changes in this edition are devoted to solid-state control technology as applied to motors. At the same time, the new methods for efficiency determination and calibration of motors that have been presented from the first edition have found commercial recognition. The determination of armature circuit losses under dynamic conditions with what we call Forgue's method has been successfully applied to diesel electric locomotive traction motors in the 900 horsepower range. When combined with rotational loss determinations as described in this book, the operating efficiency of a motor under locomotive conditions has been measured without the need for a dynamometer installation.