Open and closed position of the armature and flux linkage, Mechanical Engineering

Q. For an electromagnetic system, show that the energy stored in a magnetic field is equal to the area enclosed b/w magnetization curves for open and closed position of the armature and flux linkage - current locus during the armature moment.

Sol. Consider a simple magnetic relay. Initially the armature is in the open position. When switch S is closed, current I is established in the N turn - coil. The flux set up depends upon mmf Ni and the reluctance of the magnetic path. The magnetic field thus produced, creates North and South poles and as a result of it., there is established a magnetic force tending to shortern the air - gap.


        If the armature is not allowed to move, the mechanical work done, dWmech. Is zero.




               dWelec = 0 + dWfld


               (dWelec =   dWmech. + dWfld)


          This shows that when the movable part of any physical system is kept fixed, the entire electrical energy input is stored in the magnetic field.


                  dWfld = dWelec


and            dWfld = dWelec = i.dψ = F.dΦ


  If the initial flux is zero, then the magnetic field energy stored Wfld, in establishing a flux Φ1 or flux linkage ψ1, is given by



                  Wfld = ψ1 0(i.d ψ1 = Φ1 0(F.d Φ


I and F must be expressed in terms of ψ and Φ.

When the armature is held in open position then the most of the m.m.f. is consumed in the air - gap and it is likely that magnetic saturation may not occur.


             Wfld = Φ1 0( dWfld = Φ1 0(F.dQ = area OABO


            Wfld = ψ1 0(d. Wfld = ψ1 0(i.d ψ1 = area OABO



        Area OACO = (d. Wfld = F1 0( Φ.dF =   i1 0( ψ.di


         This area OACO is called the co - energy Wfld


W'fld = F1 0( Φ.dF =   i1 0( ψ.di


Above, ψ and Φ must be expressed in terms of F and I respectively. Co - energy has no physical significance, it is however useful in calculating the magnetic forces.


                        With no magnetic saturation,


                                   Area OABO = Area OACO


 Or                              Wfld =   W'fld


 And                     Wfld +  W'fld  = Area OCABO =  Φ1F1 = ψ1i1


In general, for magnetic circuit,


                                        Wfld =   W'fld  = 1/2 ψi = 1/2FΦ

Posted Date: 7/23/2012 1:19:41 AM | Location : United States

Related Discussions:- Open and closed position of the armature and flux linkage, Assignment Help, Ask Question on Open and closed position of the armature and flux linkage, Get Answer, Expert's Help, Open and closed position of the armature and flux linkage Discussions

Write discussion on Open and closed position of the armature and flux linkage
Your posts are moderated
Related Questions
Find speed of dynamo shaft: Q: W ith the help of belt an engine running at 200rpm drives line shaft. The Diameter of the pulley on engine is 80cm and the diameter of the pul

GENERAL TOOLS: General tools include spanners, screw drivers, files, pliers, vices, punches, mallets, chisels, grinders, drilling machine, oil and grease guns, etc.

The Baseline Dimension Command You can use this command to generate a series of dimensions from a single base point. You must already have created the first dimension in the se

General Phase of Value Engineering: Steps- 1. Prepare a strong foundation for the value study. Extension of auger in screw conveyer in hydraulic paver machine is to be do

Method of joint: How you can find out force in the member of truss by using method of joint? Sol.: In this, after determining the reactions at supports, the equilibrium

Your company received an order to machine a batch of 150 steel parts that are 73.0 mm in diameter and 250 mm in length. One of the processes is a finish turning operation. Where th

Kleins construction fr 90 degree and 180 degree angle

Pliers: Pliers are used just for gripping or wire cutting and should never be used as substitute for spanners. The following types of plier are used : (a) Side cutting pliers

Q. Show Prevailing wind conditions for plant layout? Prevailing wind conditions influence the design considerations for the location of the flare or vent stack. It is vital tha