ABSTRACT
This chapter analyzes that the automation circuits are actuating on the power relays, supplying subsequently the motors or other industrial devices with the appropriate electrical power. It describes the thermal overload relay, which has a specific utilization in protecting the motor form an overcurrent. The chapter presents the automation circuits for the most basic types of electrical motors in order to highlight the characteristics of these types of automations. The most common cases of starting a machine take place directly after the application of the START signal in the automation circuit. This START signal can be provided in the automation circuit by a human, either through the pressing of a button or with the activation of a switch. The classical automation circuit for the operation of a machine from multiple positions requires three wires, without including the wirings for the operation indication in every control position.
