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Saturday, 3 February 2018

Different Types Of Magnetic Excited Systems !

February 03, 2018 Leave a Reply

Different Types Of Magnetic Excited Systems ! 



Single Excited Magnetic System 




  • Consider an attrect armature type electromagnet relay . 
  • It is Singly Excited Magnetic System. 
  • A coil of N-turnes is wound on the magnetic core connected to a voltage source (Vs). 



  • Assuming that the armature is held fixed at the position x and the current is increased from zero to some value i. 

Hence the magnetic flux will be set up in the magnetic system. The magnitude of magnetic flux dependa on M. M. F(N*i) and the reluctance of the magnetic path.




The incremental electrical energy (dWe)  due to the flow of current i in time dt is

dW=E.i dt

B-H curve for Single Excited System

For angular movements of armature  the electromagnetic torque fora linear system is given by
T=(1/2)*(i^2)*(dL/d§)
Where §=angle


Doubly Excited Magnetic System

  • A Magnetic System which is excited by two independent source is called Doubly Excited Magnetic Circuit. 
  • The synchronous machines amd d.c. machines are the example of Doubly Excited Magnetic System. 
  • A Doubly Excited Magnetic System which consist of stator and rotor poles and windings. 
  • The stator winding have N1 turnes is energized from source V1 and the rotor winding having N2 excited from source V2 .
  • The MMFs produced by both stator and rotor winding are in the same direction and magnetic torque Tm is in the anticlockwise direction. 

The basic principle of energy conversion

dWe = dWm + dWf

Magnetic torque developed

Tm d§ =(1/2)(i^2) dLs + (1/2)(ir^2) dLr +(is) (ir) dM
Where §=anglr
Ir= rotor current
Is= stator current




Questions Related To Different Types Of Magnetic Excited Ststem:

1)how many type for Exciting to Magnetic System??
Ans: two type (1) single excited and (2) doubly excited

2)Give the formula of  The incremental electrical energy (dWe)  due to the flow of current in the Single Excited System??
Ans: dW=E.i dt

3)Give the formula For angular movements of armature  the electromagnetic torque for a linear system ???

T=(1/2)*(i^2)*(dL/d§)
Where §=angle

4)What is Doubly Excited Magnetic System??
Ans:A magnetic system which is excited by two independent source is called doubly excited magnetic circuit.

5) Give the example of Doubly Excited Magnetic System?? 
Ans:The synchronous machines and d.c. machines .

6)Give formula for satisfied the energy conversion principle in Doubly Excited Magnetic System?? 
Ans: dWe = dWm + dWf

7)Give the formula of Magnetic torque developed in Doubly Excited Magnetic System?? 
Ans:Tm d§ =(1/2)(i^2) dLs + (1/2)(ir^2) dLr +(is) (ir) dM
Where §=anglr
Ir= rotor current
Is= stator current


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