Braking Methods of Induction Motors — Lesson 7

This lesson covers the braking methods of three-phase induction motors, focusing on plugging and DC dynamic braking. It explains the concept of braking, which is used to make a machine stop quickly by dissipating kinetic energy. The lesson discusses how plugging is executed by reversing the supply phase sequence to the stator, causing the rotating field to move in the opposite direction. It also explains how DC dynamic braking works by changing the stator supply to a DC supply, creating a stationary field. The lesson further elaborates on how to calculate the braking torque in both methods.

Video Highlights

00:26 - Explanation of plugging and how it works
04:25 - Discussion on the calculation of braking torque in plugging
17:39 - Introduction to DC dynamic braking
29:12 - Discussion on the calculation of braking torque in DC dynamic braking

Key Takeaways

- Braking in induction motors is achieved by reversing the supply phase sequence to the stator in plugging or changing the stator supply to a DC supply in DC dynamic braking.
- The braking torque in both methods can be calculated using the same torque expression, assuming steady state conditions.
- In plugging, the machine will eventually start running in the opposite direction unless disconnected from the supply when it comes to a stop.
- In DC dynamic braking, the machine will eventually come to a stop with no risk of running in the opposite direction.