MCQ
To reduce the ripples in a rectifier circuit with capacitor filter:
- ARL should be increased.
- BInput frequency should be decreased.
- CInput frequency should be increased.
- DCapacitors with high capacitance should be used.
Solution:
Ripple factor may be defined as the ratio of r.m.s. value of the ripple voltage to the absolute value of the DC component of the output voltage, usually expressed as a percentage. However ripple voltage is also commonly expressed as the peak-to-peak value. Ripple factor (r) of a full wave rectifier using capacitor filter is given by
$\text{r}=\frac{0.236\text{R}}{\omega\text{L}}$
where, L is inductance of the coil and $\omega$ is the angular frequency.
or Ripple factor can also be given by
$\text{r}=\frac{1}{4\sqrt{3}\text{v}\text{R}_\text{L}\text{C}_\text{V}}$
i.e., $\text{r}\propto\frac{1}{\text{R}_\text{L}}\Rightarrow\ \text{r}\propto\frac{1}{\text{C}},\text{r}\propto\frac{1}{\text{V}}$
Ripple factor is inversely proportional to RL, C and v.
Thus to reduce r, RL should be increased, input frequency v should be increased and capacitance C should be increased.
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