194 



APPLIED SCIENCE 



through the circuit; when it stops the electricity ceases to 

 flow. 



233. Classes or Types of Dynamos. There are three 

 classes of dynamo machines on the market series, shunt, 

 and compound each one adapted for 

 special work. They differ in the man- 

 ner in which their field magnets are 

 wound. 



234. Series Machine. A series ma- 

 chine (Fig. 85) is a dynamo which 

 allows all the current produced to pass 

 through the field magnet coils by taking 

 the wire from one brush and carrying 

 it the required number of times around 



v7 Series ~ 

 Wound Dynamo. 



the field magnet, and then connecting 

 it with the external circuit. The other end of the external 

 circuit is connected with the other brush. Such a machine is 

 not usually found on the general mar- MAIN CIKCUIT 



ket, but is a common form of motor 

 made especially for traction purposes. 



235. Shunt Machine. A shunt 

 dynamo (Fig. 86) is a machine which 

 has only a portion of its total current 

 passing through the field magnet coil. 

 It is used in all cases where it is desir- 

 able to have a constant pressure voltage 

 at all loads, as in the case of the ordinary 



FIG. 86. Shunt-Wound 

 Dynamo. 



parallel or multiple system used for lighting buildings. The 

 shunt machine is used in large plants, where the diversity 



