282 ELECTRICAL MACHINERY 



built in two parts, the high tension coil being placed between 

 the two sections of the low tension coil. 



Construction of the Core. Although the iron core of a 

 modern transformer forms a continuous iron path around 

 the coil, the laminations in the form of a hollow rectangle, 

 are not in one piece, because if such were the case, the coil 

 would have to be wound through them instead of being built 

 up independent of the core. 



FIG. 173. Coils for a Shell -type Transformer, Showing How One 

 Coil is Placed Over the Other. Westinghouse Electric and Mfg. 

 Co. 



Each lamination is made of two pieces as shown by the 

 full lines of Fig. 177. In stacking them up around the 

 coils, every other one is reversed so that the joints come 

 as shown by the dotted lines. Because of this alternation 

 of the joints, the core, when built up and clamped together, 

 is very solid and has but little more reluctance than it would 

 have if each lamination were one solid piece. 



The most recent type of construction is really a modi- 

 fication of the core type; a view of one of these trans- 

 formers removed from containing case is given in Fig. 



