THE HKATIXG OF TRANSFORMERS 129 



motors ultimaU-ly pulverised as the result of exposure to the 

 combined effect of vibration and high temperature. Even at 

 present there are plenty of manufacturers who are choosing tin ii 

 insulating materials more with reference to price per yard, per 

 pound, or per gallon, as the case may be, than to whether the 

 apparatus in which it will be employed will be subject to heat, 

 ni' -isture, or vibration, orto other deteriorating influences. Most 

 electrical manufacturers are, however, desirous of employing 

 sound materials and of keeping within as conservative tempera- 

 ture limits as the competitive struggle will permit. 



" liaising the standard temperature-limit would simply result 

 in a general lowering of the price per horse-power or per 

 kilowatt. Competition would keep the manufacturer's profits 

 as low as ever, and even the customer would not benefit, since 

 hi> motors and dynamos would be subject to a greater rate of 

 depreciation. Such a result would tend to bring discredit upon 

 the electrical industry. 



" The temperature limit should be raised by small amounts 

 from year to year, keeping pace with the gradual progress made 

 in the development of improved insulating materials. It will 

 not suffice to produce one or two insulating matt rials capable of 

 al<. withstanding a high temperature, for the requirements of 



the manufacturer of dynamo-electric machinery are only met by 

 th- employment of many dilVeivnt insulating materials." 1 



1 As further hearm- upon this important >n\>\ 



i'l Annual Convent 



tin- N I . \ (fatten, in .inn.', hunt. puts the case as 



.vs : 



' at a temperature of \<M* leaves > will 



probably w*>n fail, and assuming an a. I'me f the air of 



25 degrees < limits the maxim ii tn 



1 w y 



I 



CO to s,. of tin* 



si's nn<l not t irroiin.lin.- 



In u r I !il on the 



i the 

 1 6 degree* above that of the hot oil in the uj 



8.T. K 



