SYNCHRONOUS GENERATORS 



311 



The temperature coefficient of copper may be deducted from 



the formula -. r. Thus, at an initial temperature 



(2o4.o~r^) 



= 40 C., the temperature coefficient of increase in re- 

 sistance per degree centigrade rise, is =0.00364. 



(J74.5; 



Table XLIV deduced from the formula, is given for con- 

 venience of reference. 



III. Embedded Temperature Detector Method. This method con- 

 sists in the use of thermo-couples or resistance tempera- 

 ture detectors, located as nearly as possible at the esti- 

 mated hottest spot. When this method is used, it shall, 



i i j 



r.'.'.j.v.vj 



r : T ] 



i r i 



;....].. ..1 



: 1 } 



Double-layer Winding. 



Single-Iaj'er Winding. 



FIG. 184. Methods of Locating Temperature Detectors. 



when required, be checked by Method II; the hottest spot 

 shall then be taken to be the highest value by either 

 method, the required correction factors being applied in 

 each case. Temperature detectors should be placed in at 

 least two sets of location, as shown in Fig. 184. 

 The corrections to be added to the " observable " tempera- 

 ture when Method III is used, are as follows: In the case 

 of two-layer windings, with detectors between coil sides, 

 and between coil side and core, add 5 C. to the highest 



