WHAT IS ELECTRICAL BRAKING ?

What is electrical braking and its types?

Whenever an electric motor or drive is disconnected from the supply. The speed of the motor gradually decreases and becomes zero. Braking is a generic terms used to set a described operating conditions for electric drives. Such as rapid stopping of motor, holding the shaft to a specific position,maintaining the speed to a desired value preventing from over speeding. The process done by electrical equipment is called Electrical braking.

Electrical braking is used more than mechanical braking because of this reasons.

High operating efficiency
No heat emission produced due to friction in mechanical braking
Less maintenance.

During electrical braking, the motor is made to work as a generator, it produces a negative slip and negative torque(braking torque). This is achieved by suitable changing the electrical connections of the motor.

The braking of the drive should be such as to stop the motor at the specified point of time and location, for some safety reasons, doesnt matter whether its electrical or mechanical braking.

If a motor running at some speed is disconnected from the input supply, the only opposing torque will be the load torque. The motor will stop only after the kinetic energy stored in its inertia is dissipated. When either the torque is small or the inertia is large the motor takes long time to stop. In the applications requiring frequent stops stopping time must be decreased by introducing additional opposing torque by means of electrical braking.

In some applications such as traction, lifts rapid, accurate and smooth stops us essential to prevent from accidents.

The different types of electrical braking are:

1. Regenerative braking

2. Dynamic braking

3. Plugging.

Comments

Voltage or Current. Which is the real killer?

Voltage or Current. Which is the real killer? Hey guys, This might be the most controversial this or that question after the famous chicken or egg. Lets see it clearly, It is not the high current or high voltage that kills you. Take for eg., a 24V battery can produce much higher current than the wall socket (in the range of 10-15 amps) in our home does. Still it can’t electrocute us if we touch both the terminals. So what it is? Is it the high voltage that kills us. No, it is not for sure. To get clear about this take an example of Van de graaff generator what you might have heard in high schools or in youtube videos. So a large Van de graaff generator can produce 500000 volts or 500kv , but we had seen a stranger touching the sphere with his bare hand. The reason here is the over all rated output current generated in Van de graaff is in th...

What is the function of oil in transformer?

What is the function of oil in transformer? The oil used is purposed for two main reasons; 1. Cooling 2. Insulating The oil used must possess the following properties. 1. High dielectric strength 2. Free from inorganic acid, alkali and corrosive sulphur to prevent injury to the conductor or insulation. 3. Low viscosity to provide good heat transfer 4. Free from sludging under normal operating conditions. 5. Good resistance to emulsion so that the oil may throw down any moisture entering the tank. Cooling The transformer windings dissipate waste heat, which needs to be removed. Transformer oil absorbs this heat from the windings and conducts it to the outside of the transformer, where it can be dissipated to the outside air. It is possible to build an air-cooled transformer. These are used where spillage of the insulating oil is an unacceptable hazzard. I.e., for indoor hazard. Insulation All parts which might be...

Why Transformer is rated in KVA?

Why Transformer is rated in KVA? Well there are different two reasons for this. The first reason they normally use to explain for this is depending on the losses of the transformer. Consider a single phase transformer supplying a power VICosØ to the load. The two losses that occur in transformer are copper loss and core or iron loss. This copper loss depends on the current flowing through the conductor and iron loss depends on the voltage and not on the phase angle between voltage and current(cosØ). That is the losses are independent to the power factor of the load. Hence the total losses depends upon the volt-ampere(VA), the transformer is rated in VA or KVA or MVA. The second reason is from the view point of manufacturer. The manufacturer doesn’t know the power factor of the load or the type of load connected at the consumer end. Since the power handled by the transformer depends on load pf., rated power(KW) of the transformer cannot be a satisfactory one. ...

Times Of Electric

Search This Blog