1. 5th International Scientific Conference on Energy and Climate Change
Estimation of defects in induction machine using of current space vector locus
astrit BARDHI
myrteza BRANESHI
ymer LUGA
alfred PJETRI
11-12 October 2012, Athens Greece

2. Scope of article
The aim of this article is to present a method based on the analysis of space vector locus of the stator line currents of induction machine working under fault conditions to identify on line of stator and rotor winding faults in early stage

3. Distribution of faults.

4. Distribution of stator and rotor winding faults

5. STATOR WINDING AND ROTOR BARS FAULTS IN INDUCTION MACHINE

6. Stator winding failures
Stator winding failures occurs due:
Thermal stresses
Electrical stresses
Mechanical stresses
environmental stresses
Combination of above stresses

7. Type of stator winding faulty in IM

8. Rotor bars damage of IM Rotor bars damage consist:
Cracked of rotor bars
Cut of rotor bars
Cut of rotor ring

9. ANALYSIS OF IM
IN NORMAL CONDITION

10. IM working under normal condition

11. IM working under normal condition

12. IM working under normal condition

13. Space vector of stator line currents working under normal condition

14. ANALYSIS OF IM
WITH BROKEN ROTOR BARS

15. Effect of rotor bars damage at stator line currents

16. Effect of rotor bars damage at stator line currents

17. Effect of rotor bars damage at stator line currents
The resultant of FMM of rotor circuit in case of bar damage

18. Effect of rotor bars damage at stator line current
The resultant of FMM of rotor circuit in case of bar damage

19. Effect of rotor bars damage at stator line current
Angular speed of negative sequences of MMF
rotate in opposite of rotor speed
Ω2,2 = −sΩ1 + Ω= −sΩ1+(1 − s)Ω1 = (1 − 2s)Ω1
induce at stator winding a EMF with (1 − 2s)f1
frequency

20. Effect of rotor bars damage at stator line current

21. Effect of rotor bars damage at stator line current

22. Effect of rotor bars damage at stator line current

23. Effect of rotor bars damage at stator line current
The stator line currents in case of rotor bar
damages

24. Effect of rotor bars damage at stator line current

25. Effect of rotor bars damage at stator line current

26. Space vector locus of stator line currents

27. WITH STATOR WINDINGS FAULTY
ANALYSIS OF IM
WITH STATOR WINDINGS FAULTY

28. Effect of inter-turn shorted of winding at stator line current
Normal condition
Faulty conditions

29. Effect of inter-turn shorted of winding at stator line currents
Reduce of MMF of stator phases (IW)
MMF created by inter-turn shorted is oppossite with main MMF produce by the phase windings
Reduce the active resistance of phase damages
Magnetic couple betwen phases changes

30. Effect of inter-turn shorted of winding at stator line currents
Reduce of MMF of stator phases (IW)
MMF created by inter-turn shorted is oppossite with main MMF produce by the phase windings
Reduce the active resistance of phase damages
Magnetic couple betwen phases changes

31. Effect of inter-turn shorted of winding at stator line currents
The stator line currents in case of inter-turn shorted
isA(t) = I1msin(1t + f1) + I2msin(1t + f2)
isB(t) = I1msin(1t + f1 − 1200) + I2msin(1t + f )
isA(t) = I1msin(1t + f1 − 2400) + I2msin(1t + f )

32. Space vector locus of stator line currents in case of stator winding faults

33. Space vector locus of stator line currents in case of stator winding faults

34. EXPERIMENTAL RESULTS

35. IM working under normal condition

36. IM working under broken rotor bars at half rated power

37. The modification of the stator windings

38. IM working under faulty condition at rated power with 7.5% asymmetry

39. IM working under faulty condition at rated power

40. IM working under faulty condition at rated power

41. Conclusions
The space vector (SP) locus method can be used for monitoring without interfering on the motor regime.
Induction machine faults can be detected at early stage of development.
SP locus in case of the machine working under normal condition is a circle.
SP locus of stator line currents in case of stator winding is represented by an ellipse.
SP locus of stator line currents in case of broken rotor bars is a circle, but its width is thicker than in normal condition.

42. Thank you