Transcript EMF EQUATION OF TRANSFORMER

EMF EQUATION OF
TRANSFORMER
Lecture No. 4
By. Sajid Hussain Qazi
EMF EQUATION OF
TRANSFORMER
Let,
webers
hertz
N1=Number of turns in primary
N2=Number of turns in secondary
Φm=Maximum flux in core in
= Bm*A
f= frequency of input a.c voltage in
As shown in figure below flux increases from its
zero value to its maximum value Φm in one quarter
of the cycle i.e., 1/4f seconds,
 Average rate of change of flux is;
, wb/sec or volts
•
Now, rate of change of flux per turn means induced
emf per turn
Average emf per turn= 4fΦm ,volt
If flux varies sinusoidally, then r.m.s value of induced
emf is obtained by multiplying the average value
with form factor.
Form Factor= r.m.s value/average value=1.11
r.m.s value of emf per turn = 1.11*4*f*Φm
= 4.44*f*Φm ,volt
Now, r.m.s value of the induced e.m.f in whole of the
primary winding will be;
(induced e.m.f/turn) x no. of primary turns
E1= 4.44*N1*f*Bm *A, volt ---(i)
 Similarly, r.m.s value of the induced e.m.f in whole
of the secondary winding will be;
(induced e.m.f/turn) x no. of secondary turns
E2= 4.44*N2*f*Bm *A, volt ---(ii)
 It is seen from equation (i and ii) that E1 /N1= E2/ N2=
4.44*f*Φm. It means that e.m.f/turn is same in both
the primary and secondary windings.

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Assignment Question-1
What down the construction and types of
transformers?