Measurement of the unknown inductance by using Maxwell bridge method.

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Aim:- Measurement of the unknown inductance by using Maxwell bridge method.
Apparatus:-
Digital multimeter,
Patch cords.
R2=100W=1MW,
R3=9.97KW,
C4=1mf
LX1=318mH
LX2=73 mH
Circuit Diagram:-
Theory:-
The Maxwells bridge is used an inductance is measured by comparison with a
standard variable capacitance. One of the ratio arms has a résistance and the
capacitance in the parallel.
In this bridge at the balance in condition there is no current is flow in the
galvanometer.henced the balance equation for the bridge using the admittance of
the arm 1 instead of the impedance.
ZX=(Z2* Z 3*Y1)
Where the Y1 is the admittance of the arm-1.
Z2=R2
Z3=R3
Y1=(1/R1+j)
By separating the real and imaginary term the unknown value of the resister (Rx)
and the unknown value of the capacitor (Cx) has given below.
Rx=(R2*R3/R1).
LX= (R2*R3*C1)
Advantage-
1) This bridge is very useful for measurement of a wide range of a
inductance at the power and audio frequencies.
2) The frequency does not appear in any of the two equations.
Disadvantage-
1) This bridge requires a variable standard capacitor, which may be
Vary expensive if the calibration to a high degree of the accuracy.
2) The bridge is limited the measure the low Q value.
Procedure:-
1) Study circuit on kit from panel.
2) Connect unknown inductance LX1 in circuit. Make all possible connections to
complete the network. Switch the supply on.
3) Set null point of galvanometer by adjusting variable resistance R3
4) Note values of R2, R3, C4 by removing their connections. Calculate theoretical
values of LX using L1=R2R3C4.
5) Measure actual value of LX1 using LCR meter. Compare this value with
calculated. also calculate Q factor by using above equation.
Result:- Unknown inductance measured using Maxwell’s bridge is found to be
LX1=____
Viva Questions:-
1) What are the limitations of this bridge?
2) What is the difference between this method and Hays bridge method?
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