Electrical Switches and Switch Symbols

In transformer symbols, polarity marks are used to depict current flow within a circuit, aiding in determining the phase relationship between the input and output terminals. These marks are typically represented as dots. When observing these symbols, note that the dot on the primary side signifies current entering the transformer, while the dot on the secondary side indicates current exiting. This is crucial for understanding how current flows through a transformer, as illustrated in the accompanying image.

Switches

The image below showcases the most common types of switches along with their symbols. The term "pole" refers to the number of points where current can enter a switch. The image includes examples of single pole and double pole switches, though switches can have multiple poles depending on their function. The term "throw" describes the number of circuits each pole of a switch can complete or control. This is illustrated through various switch symbols such as SPST, DPST, SPDT, DPDT, and others, which indicate different configurations and functionalities of switches in electrical circuits.