Page 330 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

2 DC Motor
A motor that converts the DC power into mechanical power is referred to as a DC electric motor. It is operated by
a DC current. The basic working principle of a DC motor is that when a current-carrying conductor is placed in a
magnetic field, a force exerted on it develops torque.
The DC motor consists of two main parts: the armature and the stator. The rotating part is the armature, and the
stationary part is the stator.

Types of AC Electric Motor

AC motors are mainly classified into three types, and they are:

• Synchronous Motor
• Asynchronous or Induction Motor
• Linear Motor
1 Synchronous Motor
The synchronous motor changes the alternating current into mechanical power at the desired frequency. In this
motor, the speed of the motor is synchronized with the AC frequency. These motors mainly depend on the three-
phase supply. In this, the motor speed is the constant speed at which the motor generates an electromotive force.

. There is no air gap available in the speed of the stator current and rotor. So it provides more rotation accuracy.
Because of high rotation accuracy, these motors are applicable in automation, robotics, etc
The synchronous motor is segmented into two types
i Reluctance Motor

The motor whose construction is similar to an induction motor and runs like a single-phase synchronous motor is
called the reluctance motor.
In this motor, the rotor is like a squirrel cage, and the stator includes sets of windings such as the auxiliary and
main windings. To offer a level operation at a stable speed, the auxiliary windings are very useful.
These motors are commonly used in signal generators, recorders, etc., which require proper synchronization.
ii Hysteresis Motor

The hysteresis motor has a uniform air gap and doesn’t have any DC excitation system. The rotor of this motor
induces hysteresis and eddy current to complete its required task. The working of a motor depends on its
construction, whether it is a single-phase or three-phase supply.
These motors provide very smooth operation with stable speed, similar to other synchronous motors. The noise
level of this motor is quite small, and due to this reason, they are used in applications where soundproof motors
are required like a sound player, audio recorder, etc.

315

CITS : E & H - Electronics Mechanic - Lesson 205 - 222