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Chapter 3: AC and DC Motors - Check Your Knowledge

By Dave Polka
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?
© 2003 ISA
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