THE TRANSFORMER. 



163 



The value of the applied voltage would then be c. 2 fr,+ r 



i.e., the drop due to the resistance of the windings as cal- 

 culated on page 130. 



The magnetic leakage is equivalent to a self-induction 

 in the transformer windings. The ratio of applied voltage 

 to current produced in Experiment XVIII., will, consequently, 

 not be a function of the resistance only, but of the resistance 

 and inductance together. 



A measurement is made of the voltage applied to the 

 primary winding, by a voltmeter connected to the primary 

 terminals, and the values corresponding to the simultaneous 

 readings of secondary current are noted. 



applied voltage 



The quotient - - will give a measure ot the 



current 



impedance of the windings. The voltage is measured on the 

 high-tension winding, and the current is measured on the 

 low-tension winding. In order to calculate the value of 

 the impedance which would produce the actual drop of 

 voltage in the transformer if placed in the secondary circuit, 

 we must divide the fraction just given by the ratio of trans- 

 formation. Thus impedance equals 



1 voltage at primary terminals 

 k ' current in secondary circuit " 



The relation between the quantities under consideration 

 is shown in the triangle, Fig. 75, where the side E D repre- 



COPPER DROP VOLTS E 



PIG. 75. TRANSFORMER VOLTAGES oj.- SHORT CIRCUIT. 



sents the impedance voltage of the windings, the side F E 

 represents the voltage overcoming resistance, and the side 



