7.a) What is leakage flux as it applies to the Iron-core transformer? How is it taken into account in the analysis of the transformer?(6)
b) The following results were obtained on a 50 KVA transformer: open circuit test-primary voltage, 3300 V; secondary voltage, 415 V; primary power, 430 W. Short circuit test - primary voltage, 124V; primary current, 15.3 A; primary power, 525 W; secondary current, full load value.
Calculate:
(1) The efficiencies at full load and at half load for 0.7 power factor.
(ii) The voltage regulations for power factor 0.7
(1) lagging,
(ii) leading
(iii) The secondary terminal voltages corresponding to
(i) and
(ii).
(10)
Reference Answer
### Part (a): Leakage Flux in an Iron-Core Transformer #### Concept In an ideal transformer, it is assumed that all the magnetic flux produced by the primary winding links with the secondary winding, and vice versa. However, in a practical iron-core transformer, this is not the case. **Leakage Flux** is defined as the magnetic flux that does not follow the intended path through the iron core to link both windings. Instead, it passes through the air or insulation surrounding the windings, linking only the winding that produces it (either the primary or the secondary) but not the other.
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