ALTERNATING-CURRENT ARCS 



and there were 14.8 amperes and 97 alternations per 

 second. 



Phase Difference in the Alternating-current Arc. As 

 was shown in Fig. 30 the current lags somewhat behind 

 the potential difference. As a result the power given to 

 the arc is not equal to the product of the current as 

 ed by an alternating-current ammeter times the volt- 

 measured by a voltmeter. In this respect the arc 

 behaves as a resistance having self-induction. The phe- 

 nomenon, however, is not due to self-induction, but to the 

 fact that the conductivity between the carbons is not so 

 good when the arc has momentarily been extinguished and 

 the gas and electrodes have become cooled as when the cur- 

 rent has been flowing. 



The existence of this apparent phase difference was 

 pointed out by Heubach 1 who found it to exist for solid 

 carbons but not for cored carbons. In the following table 

 the value for c, the power factor, is given for different car- 

 bons and with different alternations per second. 2 



1 Elecktrot. ZS., 13, 460; 1892. 



2 Duddell and Marchant, Journ. Inst. Elec. Eng., 28, 86 ; 1899. 



