DIMENSION'S OF A TBAN8FORMEB :il 



tin- - il assumption for approximate calculations, there 



i<. in practice, often need for greater accuracy. The sine-\\a\ 

 .inpti"H may in many instai:<-e> involve an error of 10 per 

 . or more, in calculations relating to alternating electricity 

 apparatus. I n the case of transformers, the relation betv 

 tin- pressure and the tlux is dependent upon the wave form of the 

 . and determinations of these quantities involve the 

 use of the " form factor" 1 of the curve. The "form factor" 

 of a curve ma\ he defined as the ratio of the square root of the 

 Q ..f the squares (r///x) of the ordinate> of tin- curve, to the 

 IH value of the ordinatt s. Thus, if we denote the form 

 r by /. we have 



f rms value of ordinates 

 ~ mean value of ordinates* 



th- -a^e of a rectangular wave, as obtained approximately 



in the winding of the armature of any ordinary generator of 



LinuouB electricity, th< :ilue and the mean value are 



il t" one another, each bring rqual to the cl'evt value of the 



>mes e(jual to unity, and this 



ie minimum possible value which it can have. In an 

 continuous-electri'i:y madii- rer, tin- e. [nation 



and llux 18 



r = 0,010 T* M 



equivalent equation f.-r any other f, .rm of curve 

 " / " may he written 



r = o,o. M. 



.11 be seen that " p-ak-l ' 



curves have hw "form factors" when the 

 i.s " peak- sent tin 



rvcs, win .\ilb 



1 Thte ten M proposed ng (nee "Alter 



