A Case Study on Braking of 3 Phase Induction Motor with High Load Using DC Injection

Abstract

There are number of applications in the real-life scenario where one needs frequent start and stop of the machine running on electric motor. The motors in such machines continues to rotate even after the power supply is cut off due to inertia which is generated because of high load that is coupled to the motor. In order to reduce and stop these motors as per requirement, different braking techniques are used. These braking techniques can be classified as mechanical and electrical braking. In mechanical braking the speed of the motor is purely reduced by using various mechanical braking. Whereas in the electrical braking reverse torque is generated. In comparison with electrical braking, mechanical braking has many disadvantages of increased maintenance, wear and tear of components of system, and also in some application the use of mechanical system is avoided because of the high compactness, hence electrical braking is preferred over mechanical braking. Dynamic braking is one of the electrical methods for stopping a 3 phase induction motor connected to high load within fraction of seconds. Stopping of motor is achieved by connecting it with Dc Injection Unit a type of dynamic braking immediately after it is turned off, and thereby rapidly stopping the motor.