ARRANGEMENT OF APPARATUS 175 



good method to arrange about one-third of the lights, well dis- 

 tributed in the station, on a separate circuit, which, in case of 

 trouble, may be switched over to the exciter battery or othei 

 reserve source. In some stations this is accomplished auto- 

 matically. 



For illuminating outdoor equipments flood-lighting has, of 

 late, been used with very great success. 



Heating. The heating of the power-house building is ordina- 

 rily, to a very great extent, done by the heat radiated from the 

 machines, and provision is often made whereby during cold 

 weather the ventilating air may be used over and over again until 

 it reaches a certain temperature. In many stations separate 

 provision must be made for heating. In some this is done by 

 means of electrical heaters, while in others complete steam-heating 

 systems are installed. In connection with these a steam-cleaning 

 plant for waste, which necessarily is used in considerable quanti- 

 ties in large stations, can readily be provided. 



Miscellaneous. Provision should, of course, also be made for 

 necessary repair shops, store rooms, offices, toilets, etc., and pro- 

 tective measures for accidents and fire must not be neglected. A 

 vacuum compressed-air system may be required for cleaning or 

 other purposes and a complete water-supply system to various 

 parts of the building is, of course, also necessary. Elevators and 

 ample stairway provision is essential so as to permit a ready access 

 to important paints, as, for example, between the generator room 

 and the switchboard gallery. 



2. ARRANGEMENT OF APPARATUS 



General Considerations. The arrangement of the apparatus 

 should be very carefully considered from the standpoint of sim- 

 plicity and reliability of operation. The purpose of the station 

 being to give reliable service consideration must also be given to 

 the causes of disturbances and means for minimizing their effects. 

 In anticipating these abnormal or so-called emergency conditions, 

 the failure of every piece of apparatus must be considered as a 

 possibility, and a definite plan worked out for limiting the mag- 

 nitude and area of such disturbances. 



Turbines. With horizontal sets the turbines may be located, 

 together with the generators, in the generator room or in separate 

 wheel chambers built in the dam or partition towards the fore- 



