174 



POWER-HOUSE DESIGN 



The total losses in generating room equals (total Kv.A. gen- 

 erator capacity) (total Kv.A. generator capacity X generator 

 efficiency). 



The total amount of air required for the generator room in 

 cubic feet per minute equals 



10,000 X total loss per hour in kw-hr. 

 ~60~~ 



The above method will give approximately twice as much 

 air as that required with the forced or positive ventilation schemes, 

 for the reason that when the ventilating scheme is such that a 

 definite amount of outside air will pass through the machine, a 

 temperature difference of 30 F. to 40 F. (16.7 C. to 22.7 C.) 

 between ingoing and outgoing air is not excessive. 



TABLE XXXVII 



QUANTITY OP Am IN CUBIC FEET DISCHARGED PER MINUTE THROUGH A 

 VENTILATING DUCT OF 1 SQUARE FOOT IN CROSS-SECTIONAL AREA. 

 DIFFERENCE IN TEMPERATURE OF AIR IN DUCT AND OUTSIDE 20 F. 



Illumination. This is mostly done by tungsten lamps, the 

 proper location and spacing, of course, being governed by- the 

 general layout and arrangement of the apparatus. In the gene- 

 rator room 500-watt lamps are used very generally and are 

 mounted on the roof trusses and provided with intensity reflectors, 

 giving a very uniform and satisfactory illumination. In addition 

 the lamps are also mounted on brackets along the walls. For 

 other parts of the station the lamps vary in size from 25 to 500 

 watts. 



The current for the lighting may be taken from the exciter 

 system, if not fluctuating too widely, or by means of step-down 

 transformers from the main bus. As a protective measure it is a 



