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, 

 HAM CIRCUIT an d 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 

 j^ ^ ne required number of times around 



FIG. 85. Series- 

 Wound Dynamo. 



fuat CIKCUIT 



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- 

 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 



