17-2 THE DESIGN OF STATIC TRANSFORMERS 



heated and rises to tin- upper part of the transformer. IJy 

 menus of a small motor the oil is pumped over to the part 

 exterior to the barrier where it cools and full to the bottom, 

 read}' to start on another journey through the transformer and 

 to abstract further heat from the active material. 



Forccd-Oil-Cooled Transformers. As an alternative to 

 employing a coil of tubes in the oil and circulating cooling 



FIG. 100. Oil-immersed transformer provided with cylindrical barrier to 

 promote circulation. 



water through the coil, there are occasions where it is more 

 advantageous to pump the oil out of the transformer, cool it, 

 and pump it back again. In the arrangement shown in Fig. 

 101 the hot oil leaving the transformer at B, is, by means of 

 the pump A, forced through the spiral pipe C, and is then 

 forced into the transformer again at D. In its passage 

 through C the heat is transferred from the oil to the cooling 

 water which is forced into and from the tank E by the pump F 

 driven by the motor G. The difference in temperature bet ween 



