484 



FARM MOTORS 



FIG. 365 BIPOLAR DIRECT-CURRENT DYNAMO 



a loss. They are known as eddy currents and the loss 

 is termed eddy current loss. Fig. 366 shows a section 

 of a solid armature and the direction of these currents. 

 Not only do these currents create a loss themselves but 

 they heat the armature windings and thus increase the 

 armature resistance. If these large eddy currents can be 

 broken up into smaller ones the loss will not be so great. 

 To break up these eddies armatures are now generally 

 built up of a large number of sheets of iron with insula- 

 tion between the sheets. The insulation used for this 



