What is a "single phase" electrical system?

A "single phase" electrical system refers to a power distribution setup that relies on a single alternating voltage waveform. This type of system is commonly used in residential wiring and smaller commercial applications. In a single-phase system, the voltage fluctuates in a sinusoidal manner, providing power continuously in one phase. This allows for a straightforward design with suitable applications that do not require the more complex or higher capacity of three-phase systems.

Single-phase systems typically deliver adequate power for basic household appliances like lights, fans, and smaller motors. While they may have limitations in terms of maximum power delivery compared to three-phase systems, they are sufficient for many everyday uses, making them an extensively employed method of electrical distribution.

In contrast, the other options describe different configurations or characteristics that do not define a single-phase system. The use of both AC and DC pertains to mixed power supply systems, while three separate voltage phases refer specifically to three-phase systems designed for more demanding electrical loads. High voltage distribution systems generally apply to utility-scale power transmission and again differ from the single-phase context, which typically operates at lower voltages suitable for residential or light commercial use.