THE LOCAXiISATION OF BKEAKS AND FAULTS. 



455 



it can be seen from the observations how the fault is behaving 

 and whether it is of large or small exposure. This test 

 approaches very closely the accuracy of the Varley loop. 



Messrs. J. Anderson and A. E. Kennelly brought out this 

 method in the year 1885 {The Electrician Vol. XV., p. 177) and 

 it has proved very successful. The principle of the test is to 

 take readings on the bridge in turn at either end of the cable, 

 the opposite end being earthed for the time, and, by adding 

 a resistance to the lower end to make both bridge read- 



L-x 



Fault 



Resistance adjusted 



to balance 

 VwwvVvw 



Distant End 

 3n Earthed 



Home End i 1 ^ 



Earthed | H^^^ -g 



L-x 



Fault 



Resistance adjusted 

 to balance 



m.. 



Zinc to line 

 Fig. 255. —Anderson and Kennelly's Earth Overlap Test. 



ings equal. This is equivalent to putting the fault electrically 

 in the centre of the line. An even bridge should be used at 

 both ends, and the current to line, as indicated on the 

 milammeter, should be the same at each end ; the current 

 through the fault will then be the same, and its resistance the 

 same for the tests from both ends. The connections for test- 

 ing at both ends of the line are given in Fig. 255. 



The tests should be taken with zinc current to line by both 

 «nds, as by this the fault is kept open and the current from 



