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