CTiriKHX: Till-: SYNCHRONOUS CONVERTER 



US, although a conductor at the exact center of the winding 

 is nut shown in that liiruro. 



A nine that the current is in phase with the induced electro- 

 motive force. When a is in position (1), Fig. 324, the alternating 

 current in the entire phase belt is zero; when a reaches position 

 lie current is a maximum; etc. This current is plotted in 

 124 (a), a sine wave being assumed The alternating current 

 is opposed to the direct current, since one is a motor current and 

 the other a generator current for the same induced electromotive 

 The resultant current is found by adding the two cur- 

 point by point, the result being shown in Fig. 324(6). This 

 resultant current is irregular in form, and its effective value is 

 small compared to that of either of the component currents. 



This resultant current, though periodic, is not a sine wave, 

 and therefore must be made up of a current wave of fundamental 

 frequency and higher harmonics. As the current is assumed to 

 be in phase with the induced electromotive force, the product 

 of this current of fundamental frequency and the induced electro- 

 motive force gives the power necessary to supply the rotational 

 losses, which include friction, windage, and core losses. 



\t consider conductor 6, Fig. 323, at one of the slip-ring 

 taps, but in the same phase belt as a. As this conductor passes 

 through the successive positions (1), (2), (3), and (4), the direct 

 current is the same for each position of 6 as it was for the cor- 

 responding position of a. This direct current is plotted in Fig. 

 /). The alternating current in // must bo the same as in </, 

 for the two are in the same phase-belt and so are in series. When 

 conductor h is in position (1), a is in position (4), and therefore 

 ii rent in both a and b is a positive maximum, from l-'ig. 324. 

 When l> reaches (2) the current is zero, etc. This current is plot ted 

 in I'IL . The resultant current is shown in Fig. 325 (6). 



It will l.e noted that the resultant current in b is distinctly 

 in magnitude than the current in n. Fig- 324 (b). There- 

 fore, the heating in the rondii irer the slip-firm taps will 



Baler than it is in the conductors midway betwi 

 On the other hand, it can be >imilarly shown that the healing 

 in conductor c. in the same phase-bell as <i and l> but at the other 

 tap. is different from the heating in either a OF 6, if tin- 

 Ifl other than unity. 



