DIMKNS10NS OF A TRANSFORMER 29 



i lame ntiinber of turns in order to obtain sufficiently 



small weights of steel and sutHdeiitly low core losses. Thus 



the values are lower than would be the case were insulation 



safety factors the only consideration, and this accounts for the 



pnesa at the start of the curves in Fig, 8, which show 



iiii -ally tin- relation between the rating, pressure, periodicity 



and r turn " obtained by an analysis of a large number 



of successful modern designs of the core type. For shell-type 



transformers the values shown may be increased by some 10 to 



, -i- cent. It >hould be mentioned that these curves are 



plotted from designs proportioned in accordance with my own 



practiee. A good many other designers prefer to employ a 



less nuinbi r i. f turns and consequently higher values than those 



: - the M volts per turn,'' and although then- 



are certain advantages attending Mich proportions, yet it may 



occur that other (very often essential) (Dualities are sacn: 



iplojment Kadi designer will, as he Min> in 

 expe :.-ailily i r himself in each rase which of 



e two tendencies b den it best to follow; but the r. 



until be has obtained hU own experi. nee, to 



curves of Fig. 9, which, while lying much higher 



values, are also much below values often 



d by some designers. It may be remarked that for 



large transformers of several thousand! of kilowatts 



capacity, the "volts per turn" assume much larger values 



D the curves. In thesr very large 

 iiictorsareco- 



> a Section, would lead to a prohibitive 

 in \\indin.u' the coiU. Tli.se strips are 



,lly inxui i.and -imultuiieoUsK with the process of 



windini! the coils. It M thus possible to instil 



ny degree require*! to ensure an ample mar-jin of | 

 with I of the " vdts p. i- tun: 



vain. tui-ii" I'.T the-e ///'/< transformers 



D from Table 1. 



