77/ /: .\LTI-:K\.\TOK 127 



PR loss whether the 4 load power-factor be unity, 0.4 or any other 

 value. The output in kiluir(itt#, however, is proportional to the 

 power-factor. If the above generator is limited to 100 amp., its 

 output will he 20 kw. at unity power-faelor hut only 8 kw. at 0.1 

 power-factor. The rating is20kv-a. (kilovolt-ampeies) regardless 

 of power-fart or. 



For the above reasons, alternators are ordinarily rated in kilo- 

 volt-amperes (kv-a.). If a machine is rated in kilowatts, unity 

 : -fact or is assumed, unless otherwise specified. In stating 

 the output of a machine 1 it is always well to state the power-factor. 



The rating of the prime-mover driving an alternator is inde- 

 pendent of the alternator power-factor. The same-turbine could 

 be used to drive a 200-kv-a. machine operating at 0.5 power- 

 factor or a 100-kv-a. machine operating at unity power-factor, 

 although the first alternator would have double the kv-a. rating 

 of the second. 



