Figure 4-6 is a wiring diagram of the same motor control system shown by the block diagram. You can see that instead of blocks being used to show components, a picture of the component is used. You can also see that the lines used to show the wiring are marked with numbers or letter-number combinations. Lines L1, L2, and L3 are incoming power leads, and the diagram shows the terminals in the starter to which they are connected, Wiring diagrams are often used along with a list of repair parts and are helpful in troubleshooting problems.

CONNECTION DIAGRAMS

Figure 4-7 is a connection diagram. It makes use of diagram symbols instead of pictures to show components. It also shows all the internal and external circuit connections. These connections can be read and traced more easily than on a wiring diagram. In the connection diagram, the components are still shown in their relative positions. This diagram may be used when you are connecting the wiring or tracing any part of the circuit. Remember that the connection diagram is a valuable troubleshooting tool. It is often found inside the cover of a piece of equipment. The dotted line indicates a single component.

Figure 4-6. - Wiring diagram.

SCHEMATIC/SINGLE-LIINE DIAGRAMS

The schematic diagram is a drawing that shows the electrical plan of operations of a piece of equipment or component. The relative position of parts is not shown in this type of diagram. The schematic diagram, like the connection diagram, makes use of symbols instead of pictures. The schematic shown in figure 4-8 is a plan

Figure 4-7. - Connection diagram.

Figure 4-8. - Schematic diagram.