Assuming leakage flux to be negligible, when HV side of a single-
| Assuming leakage flux to be negligible, when HV side of a single-phase 100 V/50 V, 50 Hz transformer is connected to 50 V, 25 Hz AC source, the core flux of the transformer is?
A. Same as that of rated flux
B. Half that of the rated flux
C. Twice that of the rated flux
D. Four times that of the rated flux
Please scroll down to see the correct answer and solution guide.
Right Answer is: A
SOLUTION
In a single-phase transformer, V1 = 100 V and f1 = 50 Hz
As there is no leakage, the core flux of the transformer is directly proportional to:
\(\phi \propto \frac{V}{f}\) ---(1)
The new values of voltage and frequency are
V2 = 50 V and f2 = 25 Hz
\(\frac{{{V_1}}}{{{f_1}}} = \frac{{100}}{{50}} = 2\)
\(\frac{{{V_2}}}{{{f_2}}} = \frac{{50}}{{25}} = 2\)
\(\Rightarrow \frac{{{V_1}}}{{{f_1}}} = \frac{{{V_2}}}{{{f_2}}}\)
The V/f ratio is constant and hence there is no change of flux.