DIMENSIONS OF A TRANSFORMER 57 



double-cotton coverings. When impregnated with suitable 

 varnishes, double-cotton coverings will be quite reliable up to 

 some 15 volts or more per turn. The external diameter of a 

 le-cotton-covered wire, whose bare diameter is 1,96 mm, 

 will be 2,11 mm. The secondary conductors will be made up 

 ot' tlut strips of a suitable section, the precise dimensions of 

 \\hi.-h, however, can only be definitely and onv. -ni.-ntly deter- 



a later stage of the calculations. 



Ih- t. -t.il (loss-section of the copper in the winding space is 

 up as follows: 



Primary copper 8100 X 0,080 = 98,0 sq cm. 



1_!1 X 0,545 = 07,5 si 

 . ot' primary and 

 secondary copper ... 98 + 67,5 = 160,5 sq cm. 



total section of copper lias to be contained in the 

 i ing space or " \\ind- >\v," but this does not OOHStil 



I nee it is desirable to employ air 



spaces between tin- windings and the con. The i>r..i 

 \\hich tin- copper section bears to tin- \\ind..\\ .xvti..n is ki: 

 as the "space factor,' and this varies both with the type of 

 Con. a of winding, and \\ith tin- piv>-mv for which the 



coils are wound. Suitable values of the space factor may 1>. 

 obtained from the curves in Fig. :U, \\lii.h apply to the 



mgular core t i . I l>od core : 



values corresponding to t be takfi 



isMimptj I observed that tl 



type, U. f ti rm eon possesses a considerably 



r a given output, and the reason 



n tin- winding ai -uted 



M p. 40, arc studi.-.l. \\ lnl.- ti 



of tl PC is wound close i stthcroi 



mdow, as sh"\M -J!, -M, p. 



