A magnetic circuit consists of two sections as shown in Figu

A magnetic circuit consists of two sections, as shown in Figure Q1(a). The coil contains 250 turns. The centre limb contains an air gap. Calculate - Total reluctance of the magnetic circuit, The current required to establish a flux density of 1 T in the centre limb, The flux densities in the outer limbs, The inductance of the magnetic circuit All dimensions are given in centimeters. The material is cast steel (refer to attached B-H curve Figure Q_1(b)).

Solution

H=(mmf)/length ; mmf=N I

I=Hxlength/number of turns

I(curent required to establish flux)= 750x(650/100)/250=19.5 (total length of flux path=0.650m) from graph H=750AT/m for B=1Tesla

Reluctance in magnetic circuit =length/(4pi*10^-7*area ); airgap length =.15cm=(.15/100)m; area of air gap=(15*25)cm²=15*25/10000 m².

substituting the values we get

Reluctance = 5.305x10⁶ Amper Turns/weber