Electrical Braking System Advantages Limitations Disadvantages
Braking System in Electric Drives - An Introduction:
To avoid danger to the worker or damage to the products quick stopping of motor is mandatory.
Due to inertia, even after disconnecting the electric supply to the running motor, it will continue to run for some time.
In many cases it is essential to stop the running motor quickly than quick starting. Delay in starting up a motor causes only the machinery to stand idle.
But a delay in stopping a motor may result in heavy damage to equipment and even the loss of human life.
Types of Braking System in Electrical Drives:
There are two types of braking used in the electrical drives namely
- Mechanical braking
- Electrical braking
In this method, the stored energy is dissipated as heat by a brake shoe or brake lining which rubs against a brake drum.
- In this method of braking, the stored energy of ratating part is converted into electrical energy and dissipated by the resistance in the form of heat or returned to the supply.
- The motors used for electric braking should have suitable braking characteristics.
- The three types of electric braking are
Rheostat or dynamic braking,
Advantage of Electrical Braking over Mechanical Braking:
- Electric braking is fast and cheap.
- In electric braking there is no maintenance cost like replaced brake shoes periodically.
- By using electic braking the capacity of the system( like higher speeds, heavy loads) can be increased.
- A part of energy is returned to the supply consequently the running cost is reduced.
- In electric braking negligible amount of heat is generated whereas in mechanical braking enormous heat is produced at brake shoes which leads to failure of brakes.
Disadvantages, Limitations of Electrical Braking:
- Electric braking can not be used for hold the machine after coming to the rest.
So a mechanical braking is required additionally.
- For example in the case of the train going up hill, after the train has been stopped using electric braking, it has to be prevented from moving down hill.
In such cases mechanical brakes also should be provided for holding.
During the braking period, the motor has to function as generator. So it must have suitable braking characteristics. ie, the choice of motor is limited.
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