The selection of control gear for a particular application is based on the consideration of

The selection of control gear for a particular application is based on the consideration of

Right Answer is:

All of the above

SOLUTION

The selection of control gear for a particular application is based on the consideration of Duty cycle, Limitation of starting current, starting torque.

Motor Selection

The first step in selecting a motor is the analysis of the requirements imposed by the application; these can be divided into three groups:

  1. Motor requirements
  2. Load requirements
  3. Control requirements.

The table given below summarizes the important considerations for each of these. On the basis of the requirements listed in Table, one can undertake the task of selecting a motor for a specific application.

 

Motor Requirement Load Requirement Control Requirement
Operating speed Determine worst-case operating conditions Available power (AC, DC)
Life span and maintenance Dynamic acceleration, full-load and overload conditions Motor operating voltage and current
Torque characteristics Starting conditions Open- or closed-loop
Mechanical aspects (size, weight, noise level, environment) Transients Forward/reverse operation
Applicable standards (e.g., radio frequency interference) Need for gearing, selection of optimum gear ratio Motoring and/or braking
Overload characteristics Frictional characteristics Torque, position, or speed control
Thermal dissipation characteristics Accuracy of speed or position control


The selection of an electric motor for any application depends on the following factors:

Selection of Electric Motor for any application

  1. Electrical characteristics
    1. Running characteristics
    2. Starting characteristics
    3. Speed control
    4. Braking characteristics
  2. Mechanical characteristics
    1. Power transmission
    2. Cooling
    3. Noise
    4. Type of enclosure
  3. Size and Rating of motors
    1. Load cycle
      1. Continuous
      2. Intermittent
      3. Variable
    2. Overload capacity
  4. Cost
    1. Initial cost
    2. Cost of control gear
    3. Running cost

For a particular application, the type of electric drive and control gear determines by the following considerations:

  1. Starting torque
  2. Duty (whether light, medium, heavy)
  3. Limitations on starting current
  4. Speed control range and its nature
  5. Need for automatic control
  6. Conditions of environment

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