THE HKATINU OF TRANSFORMERS 



119 



temperature became stationary after a run of about sixteen 

 hours, and the temperature rise after a six-hour run was, for 

 all of them, some 80 per cent, of its final value for the copper 

 ami !)<) per cent, for the iron." As regards the oil transformer 

 illustrate, 1 in Fig. 75, and to which the curves of Fig. 76 

 apply, Prof. Epstein stated : " The lower parts do not heat at 

 all at the beginning of the test. The lower the thermometer 

 is placed the greater the difference between the temperature 



77/ne >n Hours 



PICK 7<;. M. , i- ing ,: -..-- ol o I tnuwfi ra 



of tbermometen for cartel \. i'. ' ind i' > 



rise obtained after a few hours' run and tin- stationary value." 

 The diagram in I-'ig. 77 indicates the positions of the therm. >- 

 meten <-,. responding to the lour curves in IV. ~<\. I'n.l'. 

 teiO t-xplaiiird lli.' -in-jiilar shape D|' the eiii'v. s OJ 



U t'..llo\vs: 



" A^ the tran-t'..nncr becomes heated, tli.- warmed >il rises 

 the -intin. ;ui,l e,.n-, .juently the upprr therm. >nirter /> 

 will indicate the rise in t. mp. nitui.- tirst. \\hile the hwer ones 

 will ;t the beginning <.l tl. 



