188 ALTERNATING CURRENTS 



The primary current, 



j = 50,000 = n36am 



The secondary current, 



/2 = 2 2Q = 227 amp. 



The ratio of transformation 



Nt = 220 _1 

 Ni 4,400 20 



(a) #01 = 3.45 + (^] 2 0.0085 = 3.45 + 3.40 = 6.85 ohms. Ans. 



(b) #02 = 0.0085 + 3.45 = 0.00850 + 0.00863 = 



0.0171 ohm. Ans. 

 Also #02 = #01 2 = = 0.0171 ohm. Check. 



(y) 2 



(c) Xoi = 5.40 + 0.014 = 5.40 + 5.60 = 11.00 ohms. Ans. 



X 02 = 0.014 + 5.40 = 0.014 + 0.0135 = 0.0275 ohm. 



Ans. 

 Also. X 02 = t\ 2 Xoi = = 0.0275 ohm. Check. 



(d) Zoi = V(6.85) 2 + (ll.O) 2 = 12.96 ohms. Ans. 



Z 02 = \/(0.0171) 2 + (0.0275) 2 = 0.0324 ohm. Ans. 



(I \ 2 

 2^7 = 



= : = ' 0324 ohm ' Check - 



(e) P c = (11.36) 2 3.45 -f (227) 2 0.0085 = 883 watts. Ans. 



PC = /i 2 #oi = (11.36) 2 6.85 = 883 watts. Ans. 

 P e = / 2 2 #o2 = (227) 2 0.0171 = 883 watts. Ans. 



The equivalent resistance, reactance, and impedance referred 

 to either side may be used in determining the transformer charac- 

 teristics, such as regulation, efficiency, etc. That is, the trans- 

 former may be treated as a simple impedance in series with a 

 load which is connected across the line, Fig. 176 (c). If the 

 primary current and voltage are to be used, the primary equiva- 

 lent constants Z i, RQI, and X \, must be used, as is shown in 

 Fig. 176 (c). The secondary terminal voltage Vz must be multi- 



plied by the ratio of transformation (j^J as shown in Fig. 17G (c) 

 in order to refer it to the primary side. The secondary current 

 must be multiplied by (TT ) in order to refer it to the primary 

 side. The problem is then merely one of a simple series circuit. 



