6.a) Why is it important to maintain high efficiency of operation? And low values of voltages regulation for power transformers?
b) A shunt motor supplied at 230 V runs at 900 rpm. When the armature current is 30 A, the resistance of the armature circuit is 0.4 £2, calculate the resistance required in series with the armature circuit to reduce the speed to 500 rpm. Assume that the armature current is 25 Amps.
Reference Answer
### Part (a): Transformer Efficiency and Voltage Regulation #### Importance of High Efficiency of Operation High efficiency in a power transformer is of paramount importance for operational, economic, and safety reasons. Efficiency ($$\eta$$) is defined as the ratio of output power ($$P_{out}$$) to input power ($$P_{in}$$), and the difference constitutes power losses dissipated primarily as heat. $$ \eta = \frac{P_{out}}{P_{in}} = \frac{P_{out}}{P_{out} + Losses} $$
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