72 



ALTERNATING CURRENTS 



machine is fast or slow. The generator switch is usually thrown 

 when the pointer is rotating slowly in the "fast" direction and 

 is approaching the index. Figure 69 shows a General Electric 

 synchroscope and its mounting. 



To Incoming 



Machine or 



Synchronizing Bus 



Fio. 68. Typical connections for syn- 

 chroscope. 



FIG. 69. Synchronism indica- 

 tor on swinging bracket. 



41. The Oscillograph. It is often desired to investigate tran- 

 sient conditions in electrical circuits, such, for example, as the 

 current and the voltage relations during the blowing of a fuse, or 

 during the short-circuit of an alternator, or in oscillations pro- 

 duced by switching, etc. Further, it is desirable to have 

 apparatus which will show the current and the voltage waves in 

 alternating-current circuits during steady conditions. The 

 oscillograph is an instrument which is capable of meeting these 

 requirements. 



