Factors governing selection of motors

The characteristics of motors vary widely with the nature of their application and the type of duty they are expected to perform. For example, the applications like constant speed, constant torque, variable speed, continuous/intermittent duty, steep/sudden starts, frequent start/stops, etc. should be taken into consideration carefully when deciding for the type of a motor for that specific application.

electric drive motors

electric drive motors

Following factors should be considered while selecting a drive for particular application:

Nature of electric supply

  • Whether supply available is A.C. (single phase or three phase) or D.C. (pure D.C. or rectified A.C.)to be utilized for motor.
Nature of electric supply

Nature of electric supply

Nature of the drive

  • Whether motor is to drive individual machine or a group of machines.
 Individual drive

Individual drive

Nature of load

  • Whether the load requires light or heavy starting torque.
  • Whether load torque increases with speed or remains constant.
  • Whether load has heavy inertia, which may required long starting time.
Motor speed

Motor speed

Electrical characteristics of motor

  • Starting characteristics.
  • Running characteristics.
  • Speed control.
  • Braking characteristics.
Electrical characteristics of motor

Electrical characteristics of motor

Size and rating of the motor

  • whether motor is to run continuously intermittently or on load cycle.
  • Whether over load capacity and pull torque are sufficient.
Motor

Motor

Mechanical considerations

  • Type of enclosures.
  • Type of bearings.
  • Transmission of drive
  • Noise level
Mechanical considerations (motor-maintenance)

Mechanical considerations (motor-maintenance)

Cost

  • Capital cost.
  • Running cost.
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