Induction Motor Speed Control — Lesson 4

This lesson covers the problem of starting large induction motors from a direct full voltage supply and the solutions to this problem. It discusses the use of resistors in the rotor circuit for run rotor motors and the use of reduced voltage for cage induction motors. The lesson also explains the concept of reactor starting and auto transformer starting. It further delves into the speed control of induction motors, discussing the importance of starting, speed control, and electrical braking. The lesson also touches upon the use of electronic inverters for soft starting of induction motors. Towards the end, the lesson introduces the concept of using power electronics inverters to overcome the fixed supply frequency issue, thereby achieving variable voltage and frequency for speed control.

Video Highlights

00:15 - Problem of starting large induction motors and solutions
03:14 - Importance of starting, speed control, and electrical braking in induction motors
12:48 - Use of electronic inverters for soft starting of induction motors
21:00 - Introduction to the concept of using power electronics inverters for speed control

Key Takeaways

- For run rotor motors, resistors can be connected in the rotor circuit for starting. For cage induction motors, a reduced voltage is used for starting.
- Reactor starting involves connecting a reactance in line with the series, while auto transformer starting involves connecting an auto transformer.
- Speed control of induction motors is crucial and involves starting, speed control, and electrical braking.
- Electronic inverters can be used for soft starting of induction motors.
- Power electronics inverters can be used to overcome the fixed supply frequency issue, thereby achieving variable voltage and frequency for speed control.