What is the purpose of a selector switch in electrical systems?

The purpose of a selector switch in electrical systems primarily revolves around simplifying measurements and operations involving multiple circuits or phases. By allowing an operator to select which specific circuit or voltage measurement point to observe at any given time, it eliminates the need for using separate voltmeters for each phase. This efficiency not only reduces the amount of equipment needed for monitoring but also streamlines the process of taking measurements, making it easier and quicker for operators to assess electrical parameters.

The design of the selector switch enables it to connect to different terminals, thus facilitating the selection of various inputs (like different phases of a three-phase system). As the operator turns the switch to a different position, it effectively shifts the measurement point to the desired phase while utilizing a single measuring device. This makes option B the most suitable answer regarding the functionality of a selector switch in electrical systems.