The system employed for motion control(the motion may be rotational or translational) is call as an electric drive.
Advantages of Electric Drive:
1. It is simple in construction and has less maintenance cost
2. Its speed control is easy and smooth
3. It is neat, clean and free from any smoke or flue gases
4. It can be installed at any desired convenient place thus affording more flexibility in the
layout
5. It can be remotely controlled
6. Being compact, it requires less space
7. It can be started immediately without any loss of time
8. It has the comparatively longer life.
However, electric drive system has two inherent disadvantages :
1. It comes to stop as soon as there is a failure of electric supply and
2. It cannot be used at far off places which are not served by electric supply.
Classification of electric drive
1. Individual drive
In the case of an individual drive, each machine is driven by its own separate motor with the help of gears, pulley etc.
Advantage :
Most Economical.
Less maintenance.
Disadvantage:
Power loss occurs.
Group drive
In group drive, a single motor drives a number of machines through belts from a common shaft.
It is also called line shaft drive.
Advantage :
Most Economical
Disadvantage:
1. Any Fault that occurs in the driving motor renders all the driving equipment idle.
2. Efficiency low because of losses occurring in the energy transmitting mechanisms (Power loss)
3. Not safe to operate.
4. Noise level at the working spot is high.
5. Flexibility-single motor drives a no of machines through the belt form common shaft.
Multimotor drive
In multi-motor drive,s separate motors are provided for actuating different parts of the driven mechanism.
Advantage :
1. Each Machine is driven by a separated motor it can be run and stopped as desired.
2. Machines not required can be shut down and also replaced with a minimum of dislocation.
3. There is a flexibility in the installation of different machine’s.
4. In the case of a motor fault, only its connected machine will stop where as others will continue working undisturbed.
5. Absence of belts and line shafts greatly reduces the risk of a accidents to the operating personnel.
Disadvantage:
Initial high cost.