Starting of Three-Phase Induction Motor — Lesson 1

This lesson covers the process of drawing the circle diagram of a three-phase induction motor. It explains the significance of no-load and block rotor tests, and how these tests are carried out under specific conditions. The lesson also discusses the importance of choosing a current scale and how the power scale gets fixed. It further elaborates on the process of drawing the circle diagram, including the torque line and output line. The lesson also touches on the concept of operating points and how to fix them based on the motor rating. It concludes with a discussion on the starting methods of three-phase induction motors, including Direct Online (DOL) starting, reactor starting, and autotransformer starting.

Video Highlights

01:16 - Discussion on choosing a current scale and fixing the power scale
03:15 - Explanation of torque line and output line
07:08 - Concept of operating points and how to fix them
23:07 - Starting methods of three-phase induction motors

Key Takeaways

- The circle diagram of a three-phase induction motor can be drawn using the results of no-load and block rotor tests.
- The current scale is chosen first, and the power scale gets fixed accordingly.
- The operating point of a motor can be fixed based on its rating.
- There are different starting methods for three-phase induction motors, including Direct Online (DOL) starting, reactor starting, and autotransformer starting.
- For wound rotor motors, rotor resistance starting can be used to limit the starting current and improve the starting torque.