TYPES OF ELECTRICAL DRIVES

TYPES OF DRIVES:

The electric drives used in industry may be divided into three types namely

             1. Individual drive

             2. Group drive

             3. Multi motor drive

1. Individual drive:

                         In this drive, each individual load is driven by a separate motor. This motor also imparts motion to various other parts of the load.

Advantages:

Ø  Does not depends on the other drives

Ø  Better efficiency

Ø  Machines can easily be installed at any desired position.

Ø  Each operator has complete control of his machine.

Ø  The absence of belts and line shafts greatly reduces the risk of accidents.

Ø  The motor and its control can be built as an integral part of the machine which in a near appearance, cleanliness and safety.

Disadvantages:

Ø  Initial cost is high.   

Example:

Ø  Lathe

Ø  Drilling machines

Ø  Wet grinder and etc.

2. Group drive:

              In this drive single motor called main motor drives more than one loads in a single common shaft supported by bearings and pulleys.

Advantages:

Ø  It is economical. Since, single drive enough to drive multiple load.

Ø  Installation cost and cost of one single large motor will be much less than a number of smaller motors totaling the capacity.

Ø  The total HP of a group drive can be less than the sum of the HPs of the entire individual machine. Since, it is rare that the connected machines are work simultaneously.

Ø  In certain industrial process one process is connected to another process and it will be advantage if all these inter connected process is stopped simultaneously.

Disadvantages:

Ø  During fault condition carried over by shutting down the main drive. So it is affects the other operation since all the other loads are connected to common shaft.

Ø  Very difficult to make the extra provisions.

Ø  Efficiency and power factor is low all the load is not working at all times.

Ø  Constant speed and flexibility of control are not possible.

Ø  It is not possible to install any machine at distinct place.

Example:

Ø  Rice mill motor drives

3. Multi motor drives:

            In this type of drive separate motors are used for operating different parts of the same mechanism. Everyone serves to activate one of the working parts of the driven mechanism.

Advantages:

Ø  Better efficiency

Ø  Each drives controls the every one of the work parts like in horizontal and vertical position controls.

Disadvantages:

Ø  Any one of the drive is failed total mechanism was stoped.

Ø  Total cost is increased.

Example:

Ø  Conveyer belt

Ø  Metal cutting machine

Ø  Paper rolling machine and etc. 


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