186 THE TRANSFORMER. 



Case II. Secondary Circuit loaded non-inductively. (See 

 Fig. 86.) 



The only difference between the diagram for this case and 

 for the preceding is that the secondary current must be added 

 to the current (7, drawn in the previous case to represent 

 the iron-loss current. 



In order that the scale of the current flowing in the 

 secondary winding may be the same as that of current in 

 the primary, it is convenient to divide the secondary current 

 in all cases by the ratio of transformation. By this means 

 all currents represented on the diagram can be considered 

 equally effective as regards the magnetic circuit, since 

 the secondary currents flow round the core in a less number 

 of turns. Suppose that the current in the secondary circuit 

 is 20 amperes. Since the ratio of transformation is 10 to 1, 

 this must be represented on the diagram as 2 amperes. 



The length C e (7 2 is taken equal to 2 amperes. 



The magnetising current remains the same as before, and 

 the resultant primary current becomes equal to C l , which 

 is the resultant of C m , and of a current equal and 

 opposite to C 2 . The applied voltage is obtained as in 

 the previous case as the resultant of E^ and E r , where 

 O E r is taken equal to C l x R, on the scale of volts. The 

 angle of lag in the primary circuit is in this case E C^ In 

 the secondary circuit, current and voltage are in phase. 



The voltage at the terminals of the secondary winding 

 will not be E 2 , but will be less by C^ R 2 volts. This may 

 be shown on the diagram by marking off E^E^ from E^ equal 

 to O, R., K 



Where C 2 secondary current. 



E 2 resistance of secondary winding. 

 K ratio of transformation. 



Then E ?r gives the terminal voltage. 



Case III. Secondary circuit loaded inductively. (See 

 Fig. 87.) If the secondary circuit is inductive, the current, 

 instead of coinciding with the line E,, will lag behind this 

 as shown in Fig. 87, where C c C 3 is drawn of the same length 

 as in the previous case, but has an angle of lag <(> of about 

 19. 



The remaining part of the construction is exactly the 

 same as before, the primary current being again the resultant 

 of a current equal and opposite to C g and C m , and the 



