52 RATING OF ELECTRICAL MACHINERY 



GERMANY. 



Rated Pressure. Pressure. 



Above 10 \. At least 110 v. 



Prom 5,000- 7,500 v. The workim: DO T, 



Above 7,500 v. Twice the working 



GREAT BRITAIN. 



SWEDEN. 



Working Pressure 



Up to 3,300 v. .'t times tin- working with a mini- 



mum nf 7<M) v. 



vc 3,300 v. tin irorli 



UNITED STATES OF AMERICA. 



^ure. 

 Not exceeding 400 v. Hel..w 10 kw. 1,000 v. 



kw, and above. 1, :,<><) v. 



400 v. and above, but less than MM) v. Under 10 kw. 1 :.<)0 v. 



10 kw. and over. v. 



800 v. and above, but less than I.Jnov Any po ") v. 



1,200 v. and above, but less than 2,500 v. 5,000 v. 



2,500 v. and over. Double the normal 



rated voltage. 



Length of Test 



BELGIUM. 30 minutes. 



FRANCE. 30 minutes (hot) ^ j (Associtllillt , Ahaficttnrt ;, minu tes). 



GERMANY. 1 minute. 



GREAT BRITAIN. 



SWEDEN. At least 1 minute. 

 UNITED STATES. 1 minute. 



APPENDIX I. 

 HE A TING (see p. 43). 



STIPULATION OF THE MILAN CONGRESS (September, 190G). 

 The heating of a motor is to be considered as excessive when, starting 

 from a surrounding air temperature equivalent to 25 deg. cent., the motor, 

 after 10 hours' working at its permanent power or after one hour working 

 at its normal power, attains a final temperature exceeding that of the 

 surrounding air by the following values: 



(a) For windings insulated with cotton 70 deg 



For windings insulated with paper 80 " 



For windings insulated with mica, asbestos or m 

 substances presenting the same qualities of in- 

 sulation and incombustibility H> " 



(6) For commutators . . 80 " 



(c) For metallic portions in which the windings are cm- 

 bedded, the value corresponding to that indicated 

 for the windings, according to the insulation em- 

 ployed for the latter. 



When the windings are in - ith a combination of insulating 



materials, the lower limit will be taken. ... By permai r and 



normal power of a motor is to be understood that power which, the current 

 being furnished at the normal pressure of supply, can be developed by 

 the said motor during 10 consecutive hours, in the first case, and during 

 an uninterrupted period of one hour, in the second case, without the 

 heating being excessive in the sense indicated under the paragraph as 

 to " Heating." 



