Page 199 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

MODULE 15 : Industrial Programmable Systems

LESSON 93-100 : AC/DC drives

Objectives

Objectives: At the end of this lesson you shall be able to:
• state the classification types and working of AC & DC drives
• state the applications of AC & DC drives
• describe the block diagram, parts of DC drive and advantages and disadvantages of DC drives.

Electrical drives
An electric drive can be defined as an electromechanical device for converting electrical energy into mechanical
energy to feed motion to different machines and mechanisms for various kinds of process control. (Fig 1)
Motion control is required in large number of industrial and domestic applications like transportation, systems,
rolling mills, paper machines, textile mills, machine tools, fans, pumps, robots, washing machines etc.

Systems employed for motion control are called Drives, and may employ any of prime movers such as diesel or
petrol engines, gas or steam turbines, steam engines, hydraulic motors and electric motors; Supplying mechanical
energy for motion control Drives employing electric motors are known as Electrical drives. The block diagram of
an electric drive is shown in Fig 2.

Fig 1 Fig 2

Types of electric drives
i According to mode of operation
- Continuous duty drives
- Short time duty drives
- Intermittent duty drives

ii According to means of control
- Manual
- Semi automatic
- Automatic

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