Constant Voltage Transformer (CVT) and its working principle

A Constant Voltage Transformer (CVT) is a type of transformer that is used to provide a constant output voltage, even when the input voltage fluctuates. The CVT works on the principle of electromagnetic induction, which means that it uses a magnetic field to induce a voltage in a secondary winding. The primary winding of the CVT is connected to the input voltage, and the secondary winding is connected to the output load.

The key components of a CVT are the input inductor and the output capacitor. The input inductor is designed to provide a low impedance path for the input current, while the output capacitor is used to store energy and provide a constant output voltage.

How does a CVT maintain a constant output voltage?

A CVT maintains a constant output voltage due to the following factors:

1. Input Inductor: The input inductor of the CVT provides a low impedance path for the input current. This means that the input current is limited, which helps to stabilize the input voltage. As a result, the output voltage remains constant even when the input voltage fluctuates.

2. Output Capacitor: The output capacitor of the CVT stores energy and provides a constant output voltage. When the input voltage fluctuates, the output capacitor releases or absorbs energy to maintain a constant output voltage.

3. Saturation: The core of the CVT is designed to saturate at a certain input voltage. When the input voltage exceeds this level, the core becomes saturated and the output voltage remains constant.

4. Tapped Windings: Some CVTs use tapped windings to provide multiple output voltages. The tapped windings allow the CVT to provide a constant output voltage at different levels.

Conclusion:

In conclusion, a constant voltage transformer (CVT) maintains a constant output voltage due to the input inductor, output capacitor, saturation, and tapped windings. The input inductor provides a low impedance path for the input current, while the output capacitor stores energy and provides a constant output voltage. Saturation and tapped windings are additional features that allow the CVT to provide a constant output voltage at different levels.

Answer is C , 

• The CVT is non – linear transformer and works on Ferro – resonance principle. 
• The transformer operates in the magnetic saturation region as per ferro – resonance principle therefore if there is any change in the input voltage, magnetic flux does not change and output voltage remains constant. Simply, the ferro – resonance works as a flux limiter not voltage regulator.