Contactors and Relays

This course explores the fundamental principles and applications of magnetic contactors and relays in electrical control systems. You will learn how contactors operate as motor starters and in lighting applications, including proper selection of protective enclosures for various environmental conditions. The course covers electromechanical and solid-state relay operation, control relay functions, and overload protection methods in motor circuits. Learners will examine low-voltage relay control systems and interpret associated wiring diagrams. Practical troubleshooting techniques for common contactor and relay problems are included. Upon completion, learners will understand how these essential switching devices provide safe, reliable electrical control in residential, commercial, and industrial applications.

By the end of this course, you will be able to:

• Describe the operating principles and functions of magnetic contactors in electrical systems.
• Explain how motor starters operate and describe the use of contactors in motor control applications.
• Read and interpret wiring diagrams involving contactors, lighting circuits, and relay control systems.
• Describe the operating principles of electromechanical and solid-state relays and explain their functions in control circuits.
• Explain the purpose and operation of overload relays and branch-circuit protective devices in motor circuits.
• Troubleshoot common contactor and relay problems.
• Explain the operation of low-voltage relay control systems and interpret associated wiring diagrams.