ELECTRIC MOTORS
Electric motors: Types, construction , starting methods , reverse the direction of rotation in 3 types of motor motor.
Introduction
Motors convert electrical energy into mechanical energy by the interaction between the magnetic
fields set up in the stator and rotor windings. Industrial electric motors can be broadly classified
as induction motors, direct current motors or synchronous motors.
All motor types have the same
four operating components: stator (stationary windings), rotor (rotating windings), bearings, and
frame (enclosure).
fields set up in the stator and rotor windings. Industrial electric motors can be broadly classified
as induction motors, direct current motors or synchronous motors.
All motor types have the same
four operating components: stator (stationary windings), rotor (rotating windings), bearings, and
frame (enclosure).
Objective:
a. To study the construction of 3 type of motor.
b. To study the different starting methods of of 3 type of motor.
c. To study how to reverse the direction of rotation in 3 type of motor.
b. To study the different starting methods of of 3 type of motor.
c. To study how to reverse the direction of rotation in 3 type of motor.
Motor Types (chapters of course)
Induction Motors
Induction motors are the most commonly used prime mover for
various equipments in industrial applications. In induction
motors, the induced magnetic field of the stator winding
induces a current in the rotor.
This induced rotor current
produces a second magnetic field, which tries to oppose the
stator magnetic field, and this causes the rotor to rotate.
The 3-phase squirrel cage motor is the workhorse of
industry; it is rugged and reliable, and is by far the most
common motor type used in industry.
These motors drive
pumps, blowers and fans, compressors, conveyers and production lines. The 3-phase induction
motor has three windings each connected to a separate phase of the power supply.
Direct-Current Motors
Direct-Current motors, as the name implies, use direct-unidirectional, current. Direct current
motors are used in special applications- where high torque starting or where smooth acceleration
over a broad speed range is required.
Synchronous Motors
AC power is fed to the stator of the synchronous motor. The rotor is fed by DC from a separate
source. The rotor magnetic field locks onto the stator rotating magnetic field and rotates at the
same speed. The speed of the rotor is a function of the supply frequency and the number of
magnetic poles in the stator.
While induction motors rotate with a slip, i.e., rpm is less than the
synchronous speed, the synchronous motor rotate with no slip, i.e., the RPM is same as the
synchronous speed governed by supply frequency and number of poles. The slip energy is
provided by the D.C. excitation power.
Induction motors are the most commonly used prime mover for
various equipments in industrial applications. In induction
motors, the induced magnetic field of the stator winding
induces a current in the rotor.
This induced rotor current
produces a second magnetic field, which tries to oppose the
stator magnetic field, and this causes the rotor to rotate.
The 3-phase squirrel cage motor is the workhorse of
industry; it is rugged and reliable, and is by far the most
common motor type used in industry.
These motors drive
pumps, blowers and fans, compressors, conveyers and production lines. The 3-phase induction
motor has three windings each connected to a separate phase of the power supply.
Direct-Current Motors
Direct-Current motors, as the name implies, use direct-unidirectional, current. Direct current
motors are used in special applications- where high torque starting or where smooth acceleration
over a broad speed range is required.
Synchronous Motors
AC power is fed to the stator of the synchronous motor. The rotor is fed by DC from a separate
source. The rotor magnetic field locks onto the stator rotating magnetic field and rotates at the
same speed. The speed of the rotor is a function of the supply frequency and the number of
magnetic poles in the stator.
While induction motors rotate with a slip, i.e., rpm is less than the
synchronous speed, the synchronous motor rotate with no slip, i.e., the RPM is same as the
synchronous speed governed by supply frequency and number of poles. The slip energy is
provided by the D.C. excitation power.
Now go to the lecture to find out more about induction motors.