CH. XIII] 



CANDLE-POWER OF ARC LAMPS 



559 



current were supplied by a dynamo. This is shown in figures 303- 

 304 and in the tables which give the results of the Schenectady 

 tests ( 757-764). 



766. Relation between the power consumption and candle- 

 power. Besides the current passing through the arc, it is necessary 

 to know the power consumption, as it is the power consumption 

 which determines the cost of maintaining the arc. 



With direct current, the right-angle arc, for example, gave 2300 

 candle-power and required 56 volts potential difference at the arc. 

 This means a power consumption of 560 watts at the arc with 10 

 amperes. Under most circumstances, however, the current would 

 be supplied from a no volt line and this would represent power 



FIG. 303. RELATION BETWEEN CURRENT AND CANDLE-POWER. 



A The candle-power variation with right-angle carbons, with alternating, 

 direct and rectified current. 



B The candle-power variation with inclined carbons with alternating, 

 direct and rectified current. 



These curves show that rectified and direct current give approximately equal 

 illumination and that alternating current gives a much lower candle-power with 

 a given amperage. 



