What is the angle between line voltage and phase voltage in a star-connected electrical system?

What is the angle between line voltage and phase voltage in a star-connected electrical system?

• A. 0º
• B. 30º
• C. 45º
• D. 60º

Answer: (B)

In a star-connected electrical system, the phase voltage is the voltage across each individual winding or phase of the system, while the line voltage is the voltage measured between any two lines connected to the supply. In a balanced star connection, the line voltage is √3 times the phase voltage, and the angle between them is crucial for understanding the relationship between these voltages. The phase voltage lags the line voltage by an angle of 30 degrees. This relationship arises from the geometry of the phasor representation of voltages in a three-phase system. Since the line voltage is the vector sum of two phase voltages, and the phase angles are equally spaced at 120 degrees apart, the angle between the line and phase voltages results in a 30-degree difference. Therefore, the correct answer identifies this fundamental relationship in a star-connected configuration.

In a star-connected electrical system, the phase voltage is the voltage across each individual winding or phase of the system, while the line voltage is the voltage measured between any two lines connected to the supply. In a balanced star connection, the line voltage is √3 times the phase voltage, and the angle between them is crucial for understanding the relationship between these voltages.

The phase voltage lags the line voltage by an angle of 30 degrees. This relationship arises from the geometry of the phasor representation of voltages in a three-phase system. Since the line voltage is the vector sum of two phase voltages, and the phase angles are equally spaced at 120 degrees apart, the angle between the line and phase voltages results in a 30-degree difference. Therefore, the correct answer identifies this fundamental relationship in a star-connected configuration.