A block diagram consists of two basic functional units that represent system operations. The individual block symbols portray the dynamic relations between the input and output signals. The second type of unit, called a summing point, is represented by a circle with arrows feeding into it.
A convenient graphical representation of input-output behavior of a system, where the signal into the block represents the input and the signal out of the block represents the output. The flow of information (the signal) is unidirectional from the input to the output. The primary use of the block diagram is to portray the interrelationship of distinct parts of the system.
A plan, sketch, drawing, chart or graph, not necessarily representational, that explains, demonstrates or clarifies the arrangement and relationship of the parts to a whole.
The path taken by an electric current in flowing through a conductor through one complete run of a set of wires from a power source, such as a panelboard, to various electrical devices and back to the same power source. The wires used for various circuits are prescribed by codes, such as the National Electrical Code.