TRANSFORMERS 165 



indirectly; that is, to read input into the secondary of a 

 transformer used to step up to the voltage of the trans- 

 former in test. This step-up transformer should have its 

 ratio, resistance and core loss carefully measured. 



Connect the primary of the step-up transformer to 

 the secondary of the transformer in test, putting a low 

 reading ammeter in circuit to read the exciting current. 

 Read volts, watts and amperes in the secondary of the 

 step-up transformer as usual. In calculating the actual 

 core loss, subtract the C 2 R and core loss of the step-up 

 transformer from the total wattmeter reading. Con- 

 nections for this test are shown in Fig. 48. 



