Electrical Machines
•Motor is a device which converts an
electrical energy into mechanical energy.
• A.C Motors are very popularly used in
practice.
»A.C Motors are the motor can be operate on A.C supply.
Classification Of A.C Motors
•According to principle of operation
•According to speed
•According to type of current
•According to structural features
•According to location
Classification according to working principle
1. Synchronous Motors
2. Asynchronous Motors
Synchronous
motor
•A synchronous motor is a constant speed motor.
•It
can be operated over a wide range of power factors.
•It is a doubly excited machine.
Advantages
of synchronous motor
•Power factor can be controlled easily.
•Motor can work at lagging, leading & upf.
•Speed is constant and independent of
load.
Disadvantages
of synchronous motors
•It is not self starting motor.
•It requires dc excitation.
•Initial cost is very high.
•It can not be used for variable speed
drives.
•If the motor is over loaded it may fall
out of step.
•It has a tendency to Hunt.
Applications
of synchronous
motors
•It
can be used as power factor corrector
•Constant
speed applications like clocks,air
compressors & centrifugal pumps
•Improving
voltage regulation of long transmission lines
•Frequency
changers
