SOLUTION

The consideration involved in the selection of the type of electric drive for a particular application depends upon Speed control range and its nature, Starting Nature, Environmental conditions.

Motor control is required in a large number of industrial and domestic applications such as transportation systems, rolling mills, paper machines, textile mills, machine tools, fans, pumps, robots, and washing machines. Systems employed for motion control are called drives and may employ any of the prime movers.

Drives employing electric motors are known as electric drives.

or

The system which is used for controlling the motion of an electrical machine, such type of system is called an electrical drive.

Factors Affecting the Selection of Electric Drive

The selection of electric drives basically means the selection of drive motors. Following are the various factors that influence the selection of motor to drive the load:

1. The limits of speed range: The range over which the speed control is necessary, for the load, similarly how hard is it to control the speed and the speed regulation also affects the choice of the motor.
2. Motor efficiency: The motor efficiency varies as the load varies so the efficiency consideration under variable speed operation affects the choice of the motor.
3. Braking: The braking requirements from the load point of view. Easy and effective braking are the requirements of a good drive.
4. Starting requirements: The starting torque necessary for the load, the corresponding starting current is drawn by the motor also affects the selection of drive.
5. Power factor: It is well known that running motors with low power factor values is not at all economical. While the power factor vanes with the load conditions in some motors. Hence the type of load and the running power factor of the motor is the essential considerations while selecting a drive.
6. Load factor: There are a variety of types of load conditions possible Idle continuous, intermittent, impact etc. Such load variations are discussed later in the chapter. Such load variation factor and duty cycle of the motor influences the selection of drive.
7. Reliability of operation: It is important to study the conditions of stable operation of an electric drive. This includes the investigation of the reliability of the operation of an electric drive.
8. Availability of supply: The motors available are a.c. or d.c. But the availability of supply decides the type of motor to be selected for the drive.
9. Effects of supply variations: There is a possibility of frequency supply variations. The motor selected must be able to withstand such supply variations.
10. Economical aspects: The size and rating of motor decide its initial cost while the various losses, temperature rise decides its Truing cost. These economical aspects must be considered while selecting a drive.
11. Environmental effects: It Is possible that the atmosphere where an electric drive is to be used may contain some chemical gases, fumes, humidity etc. Such a contaminated atmosphere or a humid atmosphere also affects the choice of motor for a drive.