An engineer modifies the design of a 25 kVA, 1100 V/220 V transformer by replacing…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
An engineer modifies the design of a 25 kVA, 1100 V/220 V transformer by replacing the core material and using thicker conductors. Before modification the full-load copper loss was 200 W and the iron loss was 250 W. After modification the iron loss falls by 30 W and the winding resistance is halved.
(i) For the original transformer working at full load and 0.8 power factor (lagging), calculate the efficiency.
(ii) For the modified transformer working under the same conditions, calculate the new efficiency.
(iii) Compute the percentage increase in efficiency achieved by the modification.
(iv) Based on your calculations, identify which loss contributes more significantly to the efficiency improvement and justify your answer with quantitative reasoning.