Maxwell’s induction bridge

1. MAXWELL’S INDUCTANCE BRIDGE

2. INTRODUCTION Different types of AC Bridges can be used for measurement of either inductance or capacitance. We can measure unknown inductance by using MAXWELL’S INDUCTANCE BRIDGE. CONSTRUCTION: There are four different arms in which: F irst arm of the bridge contains series combination of resistance and inductance. Third arm consists of series combination of variable resistance and variable inductance. Second and fourth arm consists of resistances respectively.

3. WORKING OF THE BRIDGE

4. WORKING OF BRIDGE (CONTINUED)

5. DERIVATION In adjacent figure , parameters L1 and R1 are unknown parameters. By using MAXWELL’S INDUCTANCE BRIDGE we have to find out these parameters

6. DERIVATION The mathematical balancing condition of AC bridge is: -----(1) Where, Z1=(R1+j ω L1 ) Z2=R2 Z3=(R3+j ω L3+r3) Z4=R4 Substitute the values in eq.(1) R1R4+j ω L1R4= R2(R3+r3)+j ω L3R2 Z1.Z4=Z2.Z3

7. FINAL EQUATION Real part--- R1R4=R2(R3+r3) Imaginary part---L1R4=L3R2 From these equations : The above 2 equations are FREE FROM FREQUENCY ie the values of unknown resistance and unknown inductance does not depend upon the frequency of supply. So that ANY TYPE OF DETECTOR can be used R1= ( R3+r3) L1=  

8. PHASOR DIAGRAM