//Chapter-2, Example 2.5, Page 92 //============================================================================= clc; clear; //INPUT DATA r=0.01;//radius in m lg=10^-3;//length of air gap in m Rm=(30/2)*10^-2;//mean radius in m ur=800;//relative permeability of iron ur2=1;//relative permeability of air gap N=250;//no of turns phi=20000*10^-8;//flux in Wb u0=4*%pi*10^-7;//permeability in free space a=%pi*(r)^2;//area of cross-section in m leakage_factor=1.1 //CALCULATIONS Reluctance_of_air_gap=(lg/(u0*ur2*a));//reluctance of air gap in A/wb li=(%pi*(2*r)-(lg));//length of iron path in m Reluctance_of_iron_path=((%pi*0.3)-(lg))/(4*%pi*10^-7*800*a);//in A/wb total_reluctance=Reluctance_of_air_gap+Reluctance_of_iron_path;//in A/wb MMF=phi*total_reluctance;//in Ampere turns current_required=(MMF)/(N);//in A //OUTPUT mprintf("Thus current required is %1.2f A \n",current_required); //Including leakage //CALCULATIONS MMF_of_airgap=phi*Reluctance_of_air_gap;//in A/wb Total_flux_in_ironpath=leakage_factor*phi;//in Wb MMF_of_ironpath=Total_flux_in_ironpath*Reluctance_of_iron_path;//in A Total_MMF=MMF_of_ironpath+MMF_of_airgap;//in A/wb current_required2=Total_MMF/(N);//in A //OUTPUT mprintf("Thus current required is %1.3f A",current_required2);