This document summarizes several types of AC bridges used to measure resistance, inductance, and capacitance. It describes Maxwell's inductance bridge, which uses two known impedances and two pure resistances to measure an unknown inductance. It also discusses Hay's bridge, a modification of Maxwell's bridge that can measure higher quality factor inductors. The document outlines Schering bridge, which measures capacitance and loss of a capacitor using a loss-free standard capacitor. Finally, it briefly introduces Wien's parallel bridge, a ratio bridge used in audio-frequency R-C oscillators to measure capacitance ratios.

1. A.C.
BRIDGE
S

2. synopsis
1.Introduction.
2.Maxwell's Inductance Bridge.
3.Hay’s Bridge.
4.Schering Bridge.
5.Wein’s Bridge.

3. A.C. Bridges are those
circuits which are used to
measure the unknown
resistances, capacitance and
inductance.
Balance condition for
A.C.Bridges:
Z Z = Z Z

4. Maxwell’s inductance
Bridge
 In the Maxwell’s inductance bridge ,there
are two pure resistances used for balance
relations but on other side or arms the
two known impedances are used.
 The known impedances and the resistances
make the unknown impedances as Z1 and
Z2.Such a network is known as
Maxwell’s A.C.Bridge. As shown in fig.

5. Fig.
(R
2
+ jwL
2
)R
3
= (R
X
+ jwL
X
)R
1
R
x
= (R
2
R
3
)/R
1
L
x
= (R
3
L
2
) / R
1

6. PHASOR
DIAGRAM

7. ADVANTAGES :-
 The measuremet is independent of
frequency.
 The bridge yields simple expresseion for
inductance and resistance.
 It can measure inductance from 1H to
1000H with (+/-)2 % error.

8. Hay’s Bridge
It is also a modification of the
Maxwell’s Bridge and is particularly
useful if the phase angle of the
inductive impedance is large.
In this case a comparatively smaller
series resistance R1 is used instead of
a parallel résistance.( which has to be
of a very large value) as shown in fig.

9. L
X
= (C
1
R
2
R
3
) / (1 + w
2
R
1
2
C
1
2
)
R
x
= (w
2
C
1
2
R
1
R
2
R
3
) / (1 + w
2
R
1
2
C
1
2
)

10. PHASOR
DIAGRAM

11. Advantages :-
 It can measure inductance with high Q
i.e. Q>10.
 It can be used for measuring incremental
inductance.disadvantages :-
 It cannot measure inductance with low Q
i.e. Q<10.
 The unknown value of inductance depends
on loss of inductor & on operating
frequency.

12. Schering Bridge
Schering bridge used for the
measurement of capacitance and
dielectric loss of a capacitor.
It is a device for comparing an
imperfect capacitor C2 in terms of a
loss-free standard capacitor C1,as
shown in fig.

13. Fig.
C
x
= (C
3
R
1
) / R
2
R
x
= (R
2
C
1
)/ C
3

14. PHASOR
DIAGRAM

15. ADVANTAGES :-
 It can measure small capacitors at low
voltages precisely.
 The direct reading for Cx can be obtained
by graduating C
3
accordingly, if resistance
ration is maintained at a fixed value.

16. Wien Parallel Bridge
It is also a ratio bridge used mainly
as the feedback network in the wide
range audio-frequency R-C
oscillators.
It is may be used for the
measurement of the audio-frequency
but it is not as accurate as the
modern digital frequency meters, as
shown in fig.

17. Fig.
( R
2
/ R
4
)= ( R
1
/ R
3
) + (C
3
/C
1
)
W= 1/(R 1.R3.C1.C3) ½

18. THANK
YOU…!!!

19. GUIDED BY :-Mr. DEEPAKPATIDAR
H.O.D. (E.C.) S.O.E.

20. AnikGodha
AbhirVaidya
HarishKumawat
Priyesh
Katariya
SUBMITTEDBY->

21. SUBMITTED BY ->
*Abhir Vaidya
* Anik Godha
*Harish kumawat
*Priyesh Katariya