This lesson covers the concept of electrical breaking in three-phase induction motors. It delves into the two methods of electrical breaking, namely plugging and DC dynamic breaking. The lesson explains how plugging involves interchanging the supply terminals, which changes the phase sequence applied to a running motor. It also discusses how DC dynamic breaking involves switching the supply to a DC supply, injecting DC current into the stator, and calculating the breaking torque. The lesson further explores the concept of regenerative breaking, where the motor operates as an induction generator with a negative slip, feeding power back to the supply. An illustrative example of a vehicle on a downhill track is used to explain regenerative breaking.
00:15 - Introduction to electrical breaking of three-phase induction motors
02:26 - Calculation of breaking torque
22:55 - Concept of regenerative breaking
30:33 - Example of regenerative breaking in a vehicle on a downhill track
- Electrical breaking in three-phase induction motors involves two methods: plugging and DC dynamic breaking.
- Plugging involves interchanging the supply terminals, which changes the phase sequence applied to a running motor.
- DC dynamic breaking involves switching the supply to a DC supply, injecting DC current into the stator, and calculating the breaking torque.
- Regenerative breaking involves operating the motor as an induction generator with a negative slip, feeding power back to the supply.
- An example of regenerative breaking is a vehicle on a downhill track, where the motor's speed becomes greater than the synchronous speed, causing power to flow from the motor to the supply lines.