1. Section 07

2. Power Transmission Electrical EngineeringUmm Al-Qura UniversitySlide 2

3. Slide 3

4. Transformer Slide 4 A transformer is an electrical device that transfers power from one electrical circuit to another by magnetic coupling It is most often used to convert between high and low voltages Must be AC current; a transformer does not convert DC Uses Faraday’s law and ferromagnetic properties

5. Slide 5

6. Ideal Transformer Electrical EngineeringUmm Al-Qura UniversitySlide 6

7. Example Electrical EngineeringUmm Al-Qura UniversitySlide 7

8. Example Electrical EngineeringUmm Al-Qura UniversitySlide 8   v1v1

9. Activity Slide 9

10. Section 08

11. DC Machines Can we use the magnetic force to rotate something? Slide 11

12. Basic Concept Slide 12 Source: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdc.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdc.html

13. DC Machines Examples microwave fan hi-fi tape deck fridge mixer washing machine tumble dryer vacuum computers electric saw drill screwdriver leaf blower toothbrush hair dryer razor CD player video player clocks pond pumps toys Slide 13

14. Electric Machine Parts Slide 14

15. Electric Machine Parts Slide 15

16. Two-Pole DC Machine Slide 16

17. Four-Pole DC Machine Slide 17

18. Commutator Slide 18

19. Generated Voltage Slide 19

20. DC Motor Variables Slide 20 E A (volt)is the back EMF V T (volt)is the applied voltage T dev (N.m)is the torque developed by DC Motor T load (N.m)is the opposing load torque  m (rad/s)is the armature shaft speed = 2  rpm /60 R a (  )is the motor internal resistance I A (A)is the motor current

21. DC Generator Variables Slide 21 E A (volt)is the generated voltage V T (volt)is the load voltage T pm (N.m)is the prime-mover generated torque T dev (N.m)is the opposing motor torque  m (rad/s)is the armature shaft speed = 2  rpm /60 R a (  )is the motor internal resistance I A (A)is the motor current

22. DC Machine Equations Slide 22 E A (volt)is the generated voltage T dev (N.m)is the motor torque  m (rad/s)is the armature shaft speed = 2  rpm /60 I A (A)is the motor current Kis the machine constant  (Wb)is the magnetic flux per pole

23. Power Electric Power: Mechanical Power: Slide 23

24. Ideal DC Machine Motor IN:Electric Power OUT:Mechanical Power Slide 24

25. Ideal DC Machine Generator IN:Mechanical Power OUT:Electric Power Slide 25

26. Motor Example A DC motor having R a = 0.2 , I A = 5A, V T = 220V,  m = 1200 rpm What is: back EMF voltage? developed torque? developed power? Slide 26

27. Generator Example A DC generator having P mech = 1kW, R a = 0.3 , R L = 10  What is: electric current drawn? terminal voltage? Slide 27