1. Teknologi Elektrik (BBT 3623) Bab 2: Litar Arus Ulang Alik Satu Fasa

2. Kandungan Nilai Arus ulang alik
Litar arus ulang alik rintangan, aruhan dan kapasitan tulin
Litar siri RLC
Litar kuasa rintangan tulin
Litar kuasa aruhan tulin
Litar kuasa kapasitan tulin
Kuasa dalam litar R-X
Vektor
Kuasa kompleks dalam litar arus ulang alik
Faktor kuasa dalam litar RLC
Pembaikan faktor kuasa

3. 2.1 Introduction
Electricity is produced by generators at power stations and then distributed by a vast network of transmission lines (called the National Grid system) to industry and for domestic use.
It is easier and cheaper to generate alternating current (a.c.) than direct current (d.c.) and a.c. is more conveniently distributed than d.c. since its voltage can be readily altered using transformers.
Whenever d.c. is needed in preference to a.c , devices called rectifiers are used for conversion

4. 2.2 How Altenating Current Generated
In positions (a), (e) and (i) the conductors, EMF=0  no flux is cut
In position (c) maximum flux is cut ,EMF= maximum e.m.f. is induced.

5. 2.2 How Altenating Current Generated
In position (g), maximum flux is cut EMF= maximum e.m.f. is induced. (opposite direction)
Fleming’s right hand rule

6. Fleming’s right-hand rule,

7. 2.2 How Altenating Current Generated
In positions (b), (d), (f) and (h) some flux is cut and hence some e.m.f. is induced

8. 2.3 Nilai Arus Ulang Alik (saat). V(t)=Voltan seketika (v)
Vm=Voltan maksimum (V)
(saat).

9. 2.3 Nilai Arus Ulang Alik ISTILAH – ISTILAH VOLTAN AU
Vp(Voltan puncak) – merupakan voltan maksimum yang diambil dari rajah gelombang. Bagi gelombang AU voltan puncaknya adalah Vm .
Vp-p(Voltan puncak ke puncak) – merupakan nilai yang diambil bermula dari maksimum +ve ke nilai maksimum –ve.

10. 2.3 Nilai Arus Ulang Alik ISTILAH – ISTILAH VOLTAN AU
Va(Voltan purata) – merupakan nilai purata bagi gelombang sinus di mana nilainya adalah merupakan nilai purata yang diambil bagi keluasan di bawah garis gelombang AU. Nilainya adalah merupakan 63.7% daripada nilai voltan maksimum.

11. 2.3 Nilai Arus Ulang Alik ISTILAH – ISTILAH VOLTAN AU @
Vpmkd(Voltan punca min kuasa dua) – merupakan nilai yang terpenting di dalam litar elektrik. Kebanyakan meter menunjukkan bacaan di dalam nilai pmkd yang sama dengan 70.7% daripada nilai puncak voltan ulang-alik. @

12. 2.3 Nilai Arus Ulang Alik

13. 2.4 Gambar Rajah Gelombang Au
Gelombang Sefasa

14. 2.4 Gambar Rajah Gelombang Au
Gelombang Tidak Sefasa
D.g.e. teraruh dalam ketiga-tiga gelombang adalah sama (Vm)
Tetapi ianya tidak sampai ke nilai maksimum atau nilai sifar secara serentak
Gelombang yang melalui titik sifar (0o) diambil sebagai rujukan.
perbezaan fasa

15. 2.4 Gambar Rajah Gelombang Au
Gelombang Tidak Sefasa
Gelombang B sebagai rujukan bagi ketiga-tiganya.
Gelombang A mendahului gelombang B dengan α.
Gelombang C menyusuli gelombang B dengan β.

16. 2.4 Gambar Rajah Gelombang Au
Gelombang Tidak Sefasa

17. 2.4 Gambar Rajah Gelombang Au
Gelombang Tidak Sefasa

18. 2.4 Gambar Rajah Gelombang Au
Gambar Rajah Vektor / Fasa
Gambar Rajah Gelombang
Gambar Rajah Vektor / Fasa

19. 2.5 Litar AU - Rintangan Tulin (R)

20. 2.6 Litar AU - Aruhan Tulin (L)
(Inductive reactance)
f – frekuensi
L – aruhan (Hendry)
Arus mengekori voltan (π/2 rad)

21. 2.6 Litar AU - Aruhan Tulin (L)

22. 2.6 Litar AU - Aruhan Tulin (L)

23. 2.6 Litar AU – Kapasitan Tulin (C)
(Capacitive reactance)
f – frekuensi
C – kemuatan (Farad)
Arus mendulu voltan (π/2 rad)

24. 2.6 Litar AU – Kapasitan Tulin (C)

25. 2.6 Litar AU – Kapasitan Tulin (C)

26. 2.6 Litar AU – Kapasitan Tulin (C)

27. 2.7 Litar A.U Siri R-L
In any a.c. series circuit the current is common to each component and is thus taken as the reference phasor.
Current I lags the applied voltage V by an angle between 0˚ and 90˚ (depending on the values of VR and VL)

28. 2.7 Litar A.U Siri R-L

29. 2.7 Litar A.U Siri R-L

30. 2.7 Litar A.U Siri R-L

31. 2.7 Litar A.U Siri R-L

32. 2.7 Litar A.U Siri R-L

33. 2.7 Litar A.U Siri R-L

34. 2.8 Litar A.U Siri R-C

35. 2.8 Litar A.U Siri R-C
Impedance,

36. 2.8 Litar A.U Siri R-C

37. 2.8 Litar A.U Siri R-C

38. 2.9 Litar A.U Siri R-L-C

39. 2.9 Litar A.U Siri R-L-C
Impedance,

40. 2.9 Litar A.U Siri R-L-C
Impedance,

41. This effect called series resonance
2.9 Litar A.U Siri R-L-C
Z=R
This effect called series resonance

42. 2.9 Litar A.U Siri R-L-C

43. 2.9 Litar A.U Siri R-L-C

44. 2.9 Litar A.U Siri R-L-C

45. 2.9 Litar A.U Siri R-L-C Series connected impedances
For series-connected impedances the total circuit impedance can be represented as a single L–C–R circuit by combining all values of resistance together, all values of inductance together and all values of capacitance together
remembering that for series connected capacitors

46. 2.9 Litar A.U Siri R-L-C

47. 2.9 Litar A.U Siri R-L-C

48. 2.9 Litar A.U Siri R-L-C

49. 2.9 Litar A.U Siri R-L-C

50. 2.9 Litar A.U Siri R-L-C The phasor diagram
The phasor sum of V1 and V2 gives the supply voltage V of 100V at a phase angle of 53.13◦ leading. These values may be determined by drawing or by calculation
— either by resolving into horizontal and vertical components or by the cosine and sine rules.

51. 2.10 Power In A.C Circuits

52. 2.10 Power In A.C Circuits

53. 2.10 Power In A.C Circuits

54. 2.10 Power In A.C Circuits

55. 2.10 Power In A.C Circuits

56. 2.10 Power In A.C Circuits

57. 2.10 Power In A.C Circuits

58. 2.10 Power In A.C Circuits

59. 2.10 Power In A.C Circuits

60. 2.10 Power In A.C Circuits

61. 2.10 Power In A.C Circuits

62. 2.11 R–L Parallel A.C. Circuit
In parallel circuits, the voltage is common to each branch of the network .
Thus taken as the reference phasor when drawing phasor diagrams.

63. 2.11 R–L Parallel A.C. Circuit

64. 2.11 R–L Parallel A.C. Circuit

65. 2.11 R–L Parallel A.C. Circuit

66. 2.11 R–L Parallel A.C. Circuit

67. 2.11 R–L Parallel A.C. Circuit

68. 2.12 R–C Parallel A.C. Circuit

69. 2.12 R–C Parallel A.C. Circuit

70. 2.12 R–C Parallel A.C. Circuit

71. 2.12 R–C Parallel A.C. Circuit

72. 2.12 R–C Parallel A.C. Circuit

73. 2.12 R–C Parallel A.C. Circuit

74. 2.12 R–C Parallel A.C. Circuit

75. 2.13 L–C parallel circuit

76. 2.13 L–C parallel circuit
Theoretically there are three phasor diagrams possible — each depending on the relative values of IL and IC:

77. 2.13 L–C parallel circuit
(i) IL >IC (giving a supply current, I =IL −IC lagging V by 90◦)

78. 2.13 L–C parallel circuit
(ii) IC >IL (giving a supply current, I =IC −IL leading V by 90◦)

79. 2.13 L–C parallel circuit
(iii) IL =IC (giving a supply current, I =0).
condition is not possible in practice due to circuit resistance inevitably being present

80. 2.13 L–C parallel circuit

81. 2.13 L–C parallel circuit

82. 2.13 L–C parallel circuit

83. 2.14 LR–C parallel a.c. circuit
the phasor diagram
for the LR branch

84. 2.14 LR–C parallel a.c. circuit
the phasor diagram
for the C branch

85. 2.14 LR–C parallel a.c. circuit
the phasor diagram
for the circuit

86. 2.14 LR–C parallel a.c. circuit
Phasor diagram for I depend on Ic & ILR.
There are three possible conditions for this circuit

87. 2.14 LR–C parallel a.c. circuit
Condition (i) IC >ILR sin Ø1

88. 2.14 LR–C parallel a.c. circuit
Condition (ii) ILR sin Ø1 >IC

89. 2.14 LR–C parallel a.c. circuit
Condition (iii) IC=ILR sin Ø1
this is called parallel resonance

90. 2.14 LR–C parallel a.c. circuit
2 Methof of defining supply current I
i. Scaled phasor diagram.
ii. Polar and complex number method

91. 2.14 LR–C parallel a.c. circuit

92. 2.14 LR–C parallel a.c. circuit

93. 2.15 Power factor improvement
For a particular power supplied, a high power factor reduces the current flowing in a supply system, which consequently lowers losses (i.e. I2R losses) cheaper running cost.

94. 2.15 Power factor improvement
Industrial loads such as a.c. motors are essentially inductive (R–L) and may have a low power factor.
One method of improving (or correcting) the power factor of an inductive load is to connect a static capacitor C in parallel with the load

95. 2.15 Power factor improvement
The supply current is reduced
from ILR to I, the phasor sum of ILR and IC, and the circuit power factor improves from cos Ø1 to cos Ø2

96. 2.15 Power factor improvement

97. 2.15 Power factor improvement

98. 2.15 Power factor improvement

99. 2.15 Power factor improvement

100. SEKIAN
TERIMA KASIH