CORE Loss TESTS 



25 



by the friction loss is plotted as ordinates against the 

 amperes armature as abscissae or the open circuited 

 armature voltage due to a given excitation. A curve 

 is obtained similar in character to the open circuited 

 core loss curve. Such a test is commonly known as 

 "short circuited core loss." Fig. 7 shows the results 

 of such a test after all correction factors have been 

 applied. In making this test careful measurements 

 must be made of the resistance of the short circuited 



730 

 730 

 770 

 760 

 760 

 740 



730 



* 



^720 



700 

 690 

 680 

 670 

 660 



> 



\\ 



O /O 20 30 40 SO 60 7O SO 3O /OO S/O /2O 

 Secancfs 



Fig. 8. Deceleration Curves on a 3000 Kw., 2300 Volt, 720 R.P.M., 60 Cycle 

 3-Phase, A-C. Generator 



armature circuit including all leads, before and after 

 the test, since to obtain the true short circuited core 

 loss, the C 2 R loss must 'be subtracted. Observations 

 should be made with the short circuited armature 

 current at a value at least 200 per cent of its normal 

 full load current. 



