 The output of the single phase rectifier is not pure DC but it also contains some AC components.
 The AC component is called as ripple. The ripple factor indicates magnitude of AC component in the output.
 Higher value of ripple factor means higher AC component in the output of the rectifier.
Ripple Factor
 It is defined as the ratio of RMS value of AC component to the DC component in the rectifier output.
Ripple factor =
RMS value of AC component / DC component
 Smaller value of ripple factor means effective rectification
Equation of
Ripple Factor
The effective
value of output current is given by
I_{RMS}
= √ ( I_{DC}^{2} + I_{AC}^{2
}) …….( 1 )
I_{AC} = √ ( I_{RMS}^{2}
– ^{ }I_{DC}^{2 }) ……( 2 )
Dividing
equation ( 2 ) by I_{DC}
( I_{AC}
/ I_{DC} ) = √ ( I_{RMS}^{2}
– ^{ }I_{DC}^{2 })
/ I_{DC}^{2}
Ripple Factor
= √ ( I_{RMS}^{2} / I_{DC}^{2} – ^{ }1^{ })
Ripple Factor For Half wave
rectifier
I_{RMS }=
I_{MAX} / 2
I_{DC} =
I_{MAX} / π
Therefore, the
ripple factor for half wave rectifier is
Ripple factor =
√ [ I_{MAX} / 2 ]^{2} / [ I_{MAX} / π ]^{2} – 1
= √ [ π / 2 ]^{2}
– 1
= 1.21
 The AC component exceeds than DC component in the output of the single phase half wave rectifier.
 The AC component is 121% than the DC component.
Ripple Factor For Full wave
rectifier
I_{RMS }=
I_{MAX} / √ 2
I_{DC} =
2I_{MAX} / π
Therefore, the
ripple factor for half wave rectifier is
Ripple factor =
√ [ I_{MAX} / √ 2 ]^{2} / [ 2I_{MAX} / π ]^{2}
– 1
= √ [ π / 2√ 2 ]^{2}
– 1
= 0.48
Sr.No

Type
of Rectifier

Ripple
Factor

1

Single Phase Half
Wave Rectifier

1.21

2

Single Phase Full
Wave Rectifier

0.48

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