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EMF EQUATION OF TRANSFORMER. Lecture No . 4 By. Sajid Hussain Qazi. EMF EQUATION OF TRANSFORMER. Let, N 1 =Number of turns in primary N 2 =Number of turns in secondary Φ m =Maximum flux in core in webers = B m *A f= frequency of input a.c voltage in hertz.
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EMF EQUATION OF TRANSFORMER Lecture No. 4 By. SajidHussainQazi
EMF EQUATION OF TRANSFORMER Let, N1=Number of turns in primary N2=Number of turns in secondary Φm=Maximum flux in core in webers = Bm*A f= frequency of input a.c voltage in hertz
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.
Assignment Question-1 What down the construction and types of transformers?