1. Electric Motor

9. Motor Selection Criteria ➢ Motor type: DC, AC, single-phase, three-phase and so on ➢ Power rating and speed ➢ Operating voltage and frequency ➢ Type of enclosure ➢ Frame size ➢ Mounting details

10. Motor Selection Criteria ➢ Operating torque requirements. Note these are related to speed and power by the equation Power = torque x speed. ➢ Starting torque requirements (often a design limitation) ➢ Load variations and allowable speed variations ➢ Current supply limitations ➢ Duty cycle: how frequently the motor is started and stopped ➢ Environmental factors: temperature, corrosive or explosive atmospheres, exposure to weather or liquids and so on. ➢ Voltage variations expected: Most motors can tolerate a voltage variation up to 10%. Any more requires a special design. ➢ Shaft loadings, especially side and thrust loads which can affect the life of shaft bearings.

11. Motor Size ➢ Subfractional horsepower: 0.001 to 0.040 hp (0.75 to 30W) ➢ Fractional horsepower: 0.05 to 1.0 hp (37 to 746 W) ➢ Integral horsepower: 1 hp (746 W) and larger

12. Alternating Current Motors ➢ Induction (asynchronous) - Single-Phase Split-Phase Capacitor Permanent-Split Capacitor Shaded Pole - Three-Phase NEMA (A,B,C,D) Wound Rotor ➢ Synchronous ➢ Universal

13. AC Motor Performance

14. Single-phase AC Motor Performance

15. Three-phase AC Motor Performance

16. DC Motor ➢ Shunt-Wound DC Motors ➢ Series-Wound DC Motors ➢ Compound-Wound DC Motors ➢ Permanent Magnet DC Motors

18. DC Motor Traits ➢ Speed is adjustable by varying the voltage, which lends itself to electronic control. ➢ Direction of rotation can be reversed by reversing polarity. ➢ Acceleration is more easily controlled than with AC motors. ➢ Torque can be controlled by controlling the current supply. ➢ Dynamic braking is possible by reversing the power polarity momentarily. ➢ DC motors have a high torque-to-inertia ratio, allowing quick acceleration.

19. Wound-Rotor DC Motors

20. Brushless DC Motors

21. Shunt-wound DC Motors

22. Series-wound DC Motors

23. Compound-wound DC Motors

24. Permanent Magnet DC Motors

25. Other Types of Electric Motors ➢ Torque motors. ➢ Servomotors. ➢ Stepper Motors. ➢ Linear Motors.