THE .\L'n-:i:\ATOR 



113 



Large units must be so designed that they can withstand 

 not only the stresses incident to normal operation, but also the 

 enormous mechanical stresses which occur at short-circuit, due 

 to the attraction and repulsion of the armature currents. The 

 coil ends, unless well supported, arc likely to be draped out of 

 position by electromagnetic stresses produced by the short-circuit 

 currents. This is particularly true of turbo-alternators, whose 

 internal reactance is comparatively low, and whose short-circuit 



117. ComploN-ly-wound s tutor of MM 



alternator. 



currents, then-ton-. may -i-ideral >le ma.unit ude. Figure 



I IS illustrates the care taken in brarinir the coil-ends in one o 1 ' 

 the largest types of t url>o-alteniat>r. 



Alternator - divided into two <:eneral classes, the open 



slot and the semi-clo-ed slot. The open slot. >ho\vn in Km. 1 1 ( .) 



I the more common because the coil- can lie form-wound 



and insulated prioi tO beil 1 in the sloi^. L r i\'in^ the least 



Dry metho.l of \\inding. 



