From Motors and Drives

  1. What are the two main parts of a DC motor and what is the purpose of each?

  2. What is the purpose of the brushes?

  3. Why are the laminations in the armature skewed?

  4. What is the purpose of the commutator?

  5. What is the purpose of the commutation windings?

  6. What is the purpose of compensation windings?

  7. How is speed controlled in a DC motor?

  8. How is torque controlled in a DC motor?

  9. What is the difference between a DPFG and a TEFC motor?

  10. Identify eight ratings listed on the DC motor nameplate and briefly indicate their meanings.

  11. What is the difference between a series wound and shunt wound DC motor?

  12. How is a permanent magnet DC motor different from the other standard DC motors?

  13. How does a DC servomotor differ from a standard DC motor?

  14. What are the main components of an AC induction motor, and what is the purpose of each?

  15. How is speed determined in an AC induction motor?

  16. What determines the horsepower of a motor?

  17. What is the definition of base speed?

  18. What is the V/Hz ratio?

  19. What NEMA design class would provide the highest amount of starting torque, when connected across line power?

  20. When considering inrush current draw, which NEMA motor type requires the highest amount of current upon start-up?

  21. When reviewing NEMA frame sizes, how is the centerline shaft to foot distance determined?

  22. What is the difference between IEC and NEMA ratings?

  23. How does a synchronous motor differ from a standard AC induction motor?

  24. What is the principle of operation behind an AC vector motor?

  25. How do stepper motors differ from standard AC induction motors?

Products & Services
AC Motors
AC motors include single, multiphase, universal, induction, synchronous, and gear motors. They also include servomotors.
DC Motors
DC motors are most commonly used in variable speed and torque applications. They include brushless and gear motors, as well as servomotors.
Motor Controllers
Motor controllers receive supply voltages and provide signals to motor drives that are interfaced to motors. They include a power supply, amplifier, user interface, and position control circuitry.
AC Servomotors
AC servomotors are responsive, high-acceleration motors typically constructed as permanent magnet synchronous motors.
Brushless Motors
Brushless motors are synchronous electric motors that have a magnetically (AC induction) or electronically (DC) controlled commutation system instead of a brush-based mechanical commutation system.

Topics of Interest

Introduction Probably the easiest of drive technologies to understand is the direct current (DC) drive. This type of drive converts fixed-voltage and frequency alternating current (AC) to an...

AC Motor Types Introduction AC motors can be divided into two major categories-asynchronous and synchronous. The induction motor is probably the most common type of asynchronous motor (meaning speed...

This is the final exam for the book. Reviewing the "Check Your Knowledge" questions in each chapter would be helpful before taking this final set of questions. 1. How is line notching corrected in a...

IEC Ratings At this point, it would be helpful to briefly review IEC motor ratings and then compare IEC with NEMA. The motor market today has become more global, with IEC rated motors on equipment...

Control of Speed, Torque, and Horsepower Control of Speed The speed of a squirrel cage motor depends on the frequency and the number of poles for which the motor is wound. The higher the frequency,...