A transformer having an efficiency of 80% is operating on a 400 V and 5 kW input power supply. If th

Question

A transformer having an efficiency of 80% is operating on a 400 V and 5 kW input power supply. If the current in the secondary coil is exactly 10 A, the voltage across the secondary coil and the current in the primary coil are respectively

Professor PC Thomas Classes · Answer

(a) : The input power is $P_{in} = 5000$ W and input voltage $V_p = 400$ V. The primary current is $I_p = P_{in} / V_p = 5000 / 400 = 12.5$ A. The efficiency is 80%, so the output power is $P_{out} = 0.8 	imes 5000 = 4000$ W. Since $P_{out} = V_s I_s$ and the secondary current $I_s = 10$ A, the secondary voltage is $V_s = 4000 / 10 = 400$ V.