It is very important and useful modification of the Maxwell-Wien Bridge. In this method, the unknown inductance is measured in term of a known capacitance and resistance, as shown in figure. This method is capable of precise measurements of inductance's over a wide range of values from a few micro-henrys to several henrys and is one of the commonest and the best bridge methods.
The balanced conditions for this bridge may be easily obtained by converting the mesh of impedance C, R5 and R3 to an equivalent star with star point O by Δ /Y transformation. As seen from figure 2.
With reference to figure 2 it is sheen that
Z1 = (R1 + jωL1); Z2 = R2 ; Z3 = ZOC and Z4 = R4 + ZOD
For balance Z1Z3 = Z2Z4
(R1 + jωL1) × ZOC = R2(R4 + ZOD)
Further simplification leads to
Or, R1 = R2R4/R3
This method is cable of precise measurements of inductance over a wide range of values from a few micro-henrys to several henrys and is one of the commonest and the best bridge methods.