Question

Which one of the following options represents possible voltage polarities in a single-phase two winding transformer? Here, \( V_p \) is the applied primary voltage, \( E_p \) is the induced primary voltage, \( V_s \) is the open circuit secondary voltage, and \( E_s \) is the induced secondary voltage.

• A. \includegraphics[width=0.25\linewidth]{18.1.png}
• B. \includegraphics[width=0.25\linewidth]{18.2.png}
• C. \includegraphics[width=0.25\linewidth]{18.3.png}
• D. \includegraphics[width=0.25\linewidth]{18.4.png}

Hint:

Remember that transformer polarities depend on Lenz's law and consistent voltage directions.

Answer 1

The Correct Option is B

Step 1: Transformer voltage polarities. In a transformer: \section*{Transformer Voltage Polarities} The applied primary voltage (\(V_p\)), induced primary voltage (\(E_p\)), open circuit secondary voltage (\(V_s\)), and induced secondary voltage (\(E_s\)) are key parameters in transformer operation. In a single-phase, two-winding transformer, the polarities of the induced voltages (\(E_p\) and \(E_s\)) are always opposite to their corresponding applied voltages (\(V_p\) and \(V_s\)) due to Lenz's Law. This means that: When the top terminal of the primary winding (marked with \(V_p\)) is negative, the top terminal of the secondary winding (marked with \(V_s\)) will be positive. Conversely, when the top terminal of the primary winding is positive, the top terminal of the secondary winding will be negative. Hence, the correct option is (B).