FOUNDATION OF ELECTROTECH

3. Electrical Machines and Control

3.1 Rotating Machines

3.1.1 AC and DC Motors:
AC motors include induction and synchronous types, commonly used in appliances and industries. DC motors are used in variable speed applications. Understanding torque, speed, and efficiency helps in selecting the right motor for a task.

3.1.2 Transformers:
Transformers transfer electrical energy between circuits using electromagnetic induction. They are used for stepping voltage up or down in power distribution. Key parameters include turns ratio, efficiency, and types of losses (core and copper losses).

3.2 Control Systems

3.2.1 Manual Starters and Contactors:
Manual starters control motor operations, protecting them during start and stop. Contactors are electrically controlled switches used in automation and remote control. Star-delta starters reduce inrush current during motor start-up.

3.2.2 Programmable Logic Controllers (PLCs):
PLCs automate industrial processes using ladder logic programming. They monitor inputs and control outputs such as motors, valves, and alarms. PLCs improve efficiency, reduce errors, and enable remote system control.