19-05-2014, 04:00 PM
A.C. BRIDGES
ACBridges.pdf (Size: 365.62 KB / Downloads: 334)
Maxwell-Wien Bridge or Maxwell’s L/C Bridge
As referred to in Art. 16.2, the positive phase angle of
an inductive impedance may be compensated by the
negative phase angle of a capacitive impedance put in the
opposite arm. The unknown inductance then becomes
known in terms of this capacitance.
Heavisible-Campbell Equal Ratio
Bridge
It is a mutual inductance bridge and is used for
measuring self-inductance over a wide range in terms of
mutual inductometer readings. The connections for
Heaviside’s bridge employing a standard variable mutual
inductance are shown in Fig. 16.13. The primary of the
mutual inductometer is inserted in the supply circuit and
the secondary having self-inductance L2 and resistance R2
is put in arm 2 of the bridge. The unknown inductive
impedance having self-inductance of L1 and resistance R1
is placed in arm 1. The other two arms have pure
resistances of R3 and R4.
Schering Bridge
It is one of the very important and useful methods of measuring the capacitance and dielectric
loss of a capacitor. In fact, it is a device for comparing an imperfect capacitor C2 in terms of a loss-
free standard capacitor C1 [Fig. 16.16 (a)]. The imperfect capacitor is represented by its equivalent
loss-free capacitor C2 in series with a resistance r [Fig. 16.16 (b)].