Understanding Motor Controls

Understanding Motor Controls assumes that the student has no knowledge of motor controls. The student is expected to have knowledge of basic Ohm’s law and basic circuits, such as
series, parallel, and combination. The book begins with an overview of safety. A discussion of
schematics (ladder diagrams) and wiring diagrams is presented early. The discussion of schematics and wiring diagrams is intended to help students understand the written language of
motor controls. Standard NEMA symbols are discussed and employed throughout the book
when possible. The operation of common control devices is presented to help students understand how these components function and how they are used in motor control circuits. Basic
control circuits are presented in a manner that allows students to begin with simple circuit
concepts and progress to more complicated circuits.
The textbook contains examples of how a schematic or ladder diagram is converted into
a wiring diagram. A basic numbering system is explained and employed to aid students
in making this conversion. This is the most effective method I have found of teaching a
student how to make the transition from a circuit drawn on paper to properly connecting
components in the field.
Understanding Motor Controls also covers solid-state controls for both DC and AC
motors. Variable frequency drives and programmable logic controllers are covered in detail. I explain how to convert a ladder diagram into a program that can be loaded into a
PLC. The book contains many troubleshooting problems that help the student understand
the logic of a control system. Circuit design is also used to help the student develop the
concepts of circuit logic.