Classification Of AC Motors & Adv and Dis advantages of Synchronous Motor

In the earlier post I posted about the Synchronous Motor But Before That it is very Important To Know About The Classification Of Ac Motors 

Firstly what we know about the AC Motors 

After Introducing the Dc machines (Gens & Motor) It became it is very difficult to control speeds and the system in the AC  the it is necessary to use the AC Machines

Classification Of Ac Motors :

As we Know that AC Motors Are Classified On Different Basis

Such as 
• Principle of Operation
•Speed
•Type Of Current
•Structural Features
•Location

According To Principle Of Operation AC Motors Are Classified into 2 Types

1) Synchronous Motor
   
Basically Synchronous Motor will not be used in any place only Synchronous Generator will be used

2) Asynchronous Motor

It will be A Induction Motor *We will post about this on the feature


According To Type of Current :

1) 1-ph Motors

2) 3-ph Motors

According To Speed :

1) Constant Speed
2) Adjustable Speed
3) Variable Speed

According To Structural Feature :

1) Open Type
2) Closed Type
3) Semi Closed Type

According To location:

1) Surface Type
2) Submersible


Advantages Of Synchronous Motors :

•Power factor can be controlled easily.

•Motor can work at lagging, leading & upf.


•Speed is constant and independent of load.

Dis Advantages 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

Synchronous motor Principle & Working

Introduction To Synchronous Motor :

Synchronous Motor

•Constant speed fixed by system frequency
•DC for excitation and low starting torque
•suited for low load applications
•Can improve power factor 
•suited for high electricity use systems




Synchronous speed (Ns):

Ns = 120 f / P

Where. Ns--Synchronous speed

          F- Frequency

         P- No of poles

Principle

A synchronous motor is an AC motor, which runs at constant speed fixed by frequency of the system. 

It requires direct current (DC) for excitation and has low starting torque, and synchronous motors are therefore suited for applications that start with a low load, such as air compressors, frequency changes and motor generators. 

Synchronous motors are able to improve the power factor of a system, which is why they are often used in systems that use a lot of electricity.

This motor rotates at a synchronous speed, which is given by the following equation 

Ns = 120 f / P

Where:

f = frequency of the supply frequency

P= number of poles

Working Of Synchronous Motor Or Generator

•Synchronous machines employed to convert electric energy to mechanical energy

•To present the principles of Synchronous motor, a 2-pole synchronous motor considered

It has the same basic speed, power, & torque equations as Syn. Gen. 

•Syn. Motor is the same in all respects as Syn. Gen., except than direction of power flow

•Since the direction of power flow reversed, direction of current flow in stator of motor may also be reversed

•Therefore its equivalent circuit is exactly as Syn. Gen. equivalent circuit, except that the reference direction of IA is reversed  

Advantages & Disadvantages [Click Here]

1) Synchronous condenser is a synchronous motor with

a)Over excitation     

b)Under excitation

c)Normal excitation

d)All of the above

 2) Synchronous motor is a

a) Constant speed Motor

b) Variable speed Motor

c) Adjustable speed

d) None of the above

Comment Your answers below .......