In the electrical industry, a schematic diagram is necessary to describe the design of appliance. Schematic diagrams are needed for the maintenance and repair of different equipment and electromechanical systems.
A schematic diagram represents the components of a certain system. Diagrams don't show us realistic pictures, but rather graphic symbols. The schematic diagram is designed to convey the definite information. Details that are not relevant to this information are not shown. In addition, they are often completed with special unrealistic elements that help us to understand the diagram. So that, the information is represented without unnecessary visual clutters. In an electronic circuit diagram, the location of the symbols may not be similar to the location in the physical circuit. In the schematic diagram, the symbolic elements are located to be more easily interpreted.
There are also so-called semi-schematic diagrams. They can combines some of the graphic symbols of a purely schematic diagram with other elements represented the most realistic, for various reasons.
Schematic diagrams are widely spread in service manuals to assist in understanding the interconnections of the equipment parts. Schematic diagrams provide various graphical instructions to help the users to perform dismantling and recovery mechanical assemblies. A significant number of pages with schematic diagrams are included in a lot of service and repair manuals.