(Solved): B. A 100kVA, transformer has primary and secondary voltages of 11kV and 415V respectively. i. ...

B. A $100\mathrm{kVA}$, transformer has primary and secondary voltages of $11\mathrm{kV}$ and $415\mathrm{V}$ respectively. i. Draw the no load phasor diagram and determine the values of the magnetising and core components of the no load current. Previous measurements for this size of transformer have found that the iron loss is 990 watts when the no load current was 0.5 amperes. ii. During a short circuit test on the same transformer the primary resistance was $2\Omega$ and the secondary resistance was found to be $0.01\Omega$. Determine the efficiency of the transformer when it is delivering full load at $0.8$ power factor. iii. Draw the full phasor diagram to illustrate the primary and secondary transformer currents when working under the above conditions. Calculate the current $I_1$ and ensure it matches the current derived graphically.