What is the difference between single-phase and three-phase AC systems?

What is the difference between single-phase and three-phase AC systems?

• A. Single-phase has a higher voltage than three-phase
• B. Single-phase systems have one waveform, while three-phase has three waveforms offset by 120 degrees
• C. Three-phase systems are used only in residential applications
• D. Single-phase systems are the most efficient

Answer: (B)

The correct choice highlights that single-phase systems operate with one alternating current (AC) waveform, while three-phase systems utilize three separate waveforms that are each offset by 120 degrees. This fundamental difference in waveform structure leads to several distinct advantages for three-phase systems. In a single-phase system, the electrical power is delivered through just one alternating current line, which means that the voltage and current vary in a sinusoidal manner over time. In contrast, the three-phase system’s three waveforms work together to provide a more stable and continuous power supply. This results in higher overall power capacity and efficiency, making three-phase systems especially suitable for industrial applications where machinery and heavy loads are common. The other options do not accurately depict the differences between the two systems. For example, three-phase systems are not confined to residential use; they are typically found in commercial and industrial settings due to their greater efficiency and ability to handle higher loads. Single-phase systems do not inherently have higher voltage, and they aren't necessarily more efficient than three-phase systems. The configuration and operation of each type of system determine their efficiency and suitability for various applications.

The correct choice highlights that single-phase systems operate with one alternating current (AC) waveform, while three-phase systems utilize three separate waveforms that are each offset by 120 degrees. This fundamental difference in waveform structure leads to several distinct advantages for three-phase systems.

In a single-phase system, the electrical power is delivered through just one alternating current line, which means that the voltage and current vary in a sinusoidal manner over time. In contrast, the three-phase system’s three waveforms work together to provide a more stable and continuous power supply. This results in higher overall power capacity and efficiency, making three-phase systems especially suitable for industrial applications where machinery and heavy loads are common.

The other options do not accurately depict the differences between the two systems. For example, three-phase systems are not confined to residential use; they are typically found in commercial and industrial settings due to their greater efficiency and ability to handle higher loads. Single-phase systems do not inherently have higher voltage, and they aren't necessarily more efficient than three-phase systems. The configuration and operation of each type of system determine their efficiency and suitability for various applications.