278 



ARMATURE CONSTRUCTION 



Before applying this tape, it must be dried in a vacuum oven 

 for a number of hours, and must not be taken from the oven 

 until immediately prior to use. The taped conductors are next 

 thoroughly dried in a vacuum oven, 1 and are afterwards subjected 

 to one or more dippings in some suitable impregnating varnish, 2 

 each dipping being followed by vacuum oven -dry ing. 



The conductors are again made up into groups of four, and are 

 covered first with wrappings of empire cloth and afterwards with 

 another serving of cambric tape, wound on with the machine 

 already shown in Fig. 328 or Fig. 329. This outer serving of tape 

 is mainly for the purpose of giving stability to the completed coil, 



Insulated Conductor I'TJ Z 



nductors 



-Slot Lining ' 



FIG. 330. Section of Slot of 10 h.p. 500-volt Motor. 



which is again subjected to the dipping and drying process, and 

 is then sent to the stores pending its being requisitioned for 

 assembling on the armature. 



Let us next consider the case of a 4-pole 10-h.p. motor for 500 

 volts and 950 r.p.m. A cross-section through the slot of this 

 machine is given in Fig. 330. 8 End and plan views of the winding 

 are given in Fig. 331. The windings as arranged in place on the 



1 A number of types of vacuum ovens are described in Chap. xx. of The 

 Insulation of Electric Machines. 



2 The subject of insulating varnishes is fully discussed in Chap. viii. of 

 The Insulation of Electric Machines. 



3 The thickness of the vertical insulation between the coils of wire is 

 exaggerated in Fig. 330. 



