264 ELECTRICAL MACHINERY 



until the first two conditions have been satisfied and the 

 synchronoscope needle points to this mark. 



Use of Lamps Instead of a Synchronoscope. Fig. 160 

 shows how lamps may be used on low voltage machines. If 

 the machine were a 110-volt alternator, two 110- volt lamps 



FIG. 159. Rotating Synchronoscope. Westinghouse Elec. and Mfg. 



Co. 



would be used; with a 220-volt alternator, 220- volt lamps 

 would be proper, or, of course, .two 110-volt lamps in series 

 might be used instead of each 220-volt lamp. 



Difference in Frequency Shown by the Lamps or Syn- 

 chronoscope. In synchronizing, either with lamps or a 

 synchronoscope, the incoming machine is brought up to 

 approximately its proper speed and then its voltage is 

 adjusted until equal to the bus voltage. In case a syn- 



