\NDARDIZAT10N RULES OF THh A / E . 27 



until the transformer baa beta for a sufficient time to attain 



the ire elevation due to core lota. With transformers for com- 



mercial lighting, the .!-. -he rated-load test may be taken as three 



hours, unless otherwise specified. 



KEACTOH ^REGULATORS. EJectnccir 



by resistance and other parts by thermometer. 60 deg. cent. 



d. l.MM.H Art-Ai. urge generators, motor*, transfonnert. or other 



apparatus in which reliability and reserve overload capacity are important, 

 are frequently specified not to rise in temperature more than 40 da*. 

 i load and 56 deg. cent, at rated overload !.:. how- 

 it narily undesirable to specify lower temperature elevations than 

 at rated load, measured aa ar> 



(>) RBEOSI 



287 HBATIBS and othr: hermal apparatus, no corn- 



bus' nflammable part or material, or portion liable to come in 



nth such material, should rise more than 50 deg. cent, above the 

 surrounding air under the service conditions for which it is designed. 

 188 j 1' \KTHOF RHEOSTATS. Parts of rheostats and similar apparatus nung 

 in temperature, under the specified service conditions, more than 60 deg. 

 ontain any combustible material, and should be arranged 

 hat neither they, nor the hot air issuing from 

 them, can come in contact with combustible material. 



l.i MI is RECOMMENDED IN SPECIAL CASKS. 



269 ; HKAT KEM-I. v i apparatus in which the insu- 



lating materials have special heat-resisting qualities, a higher temperature 

 elevation is permtssi 



290 .V iUi.ti AIR TEMPER AT t: RK. In apparatus intended for service in 

 places of abnormally high temperature, a lower temperature elevation 

 should be specif i 



291 c. APPARATUS SUBJECT TO OVERLOAD. In apparatus which by the 



service may be exposed to overload, or is to be used in very 



high voltage a small- temperature is desirable than in 



apparatus not liable to overloads or in low -voltage apparatus. In ap- 



itus built for conditions of limited space, as railway motors, a higher 



f temperature must be allowed. 



292 d. APPARATUS FOR IMI-KMIIII M SKKVKK In the case of apparatus 



r. except railway motors, the temperature 



elevation which is attained at the end of the period corresponding to the 



he values specified for machines 



in general. In such apparatus, including railway motors, the temperature 

 a lion should be measured after operation, under as nearly as pos- 

 sible th' ns of service for which the apparatus is intended, and 



! be specified. 



H *t 'VKKI.OAD CAP.V 



293 I'nuokM\st H \\IIH OVERLOAD. AH apparatus should be able to carry 

 the overload hereinafter specified without sen ng. spark* 



ss. etc.. and with an additional temperature rise not 

 leg. cent., above those specified for rated loads, the overload 

 being applied after the apparatus has acquired the temperature corre- 

 sponding to rated load continuous operation. Rheostats to which no 

 temperature nse limits are attached are naturally exempt from this addi- 

 tional temperature rise of 15 deg. cent, under overload specified in these 

 rules. 



294 N . - K M v .id guarantees should refer to normal con- 



ns of operation regarding speed, frequency, voltage, etc.. and to non- 

 inductive ci.t n alternating apparatu where a phase dis- 

 placement is inherent in the apparatus. 



