In the circuit shown in Fig. 1, T is s practical transformer whose turns ratio n1?/n2? is 2 , where n1? and n2? are the number of turns of the primary winding and the number of turns of the secondary winding, respectively; Vs? is a sinusoidal voltage source whose phasor voltage is \( 240 \mathrm{v} 2\left\llcorner 45^{\circ} \mathrm{V}\right. \) and whose frequency is 60 Hz; Zload represents the load of the transformer and is made of a 0.4? resistor in series with a 0.5mH inductor. Fig. 2 shows the equivalent circuit of the transformer and the load reflected to the primary side. In the circuit, R1=0.01?;Lk1?=10?H;LM?=100mH;RM?=100?;R2?=0.02?;Lk2??=15?H. 1. Find Zload', the impedance of the load transferred to the primary side (Hint: recall impedance transfer for an ideal transformer) 2. Find phasor current I1 3. Find phasor voltage VM? 4. Find phasor current 12' 5. Find power loss of the transformer, i.e., total active power of R1,R2?, and RM? 6. Find total reactive power absorbed by the transformer, i.e., total reactive power of Lk1?,Lkk2?, and LM? 7. Find active power and reactive power of the load
8. Do you think it will cause large error in the above results if you consider LM? and RM? as infinity, i.e., open circuit, so that you can simplify the equivalent circuit into the one shown in Fig. 3 (see the next page)? Why? Fig. 1
Fig. 1 Fig. 2
Fig. 3