176 POWER-HOUSE DESIGN 



bay. The latter practice is only used for very low-head develop- 

 ments, where one of the power-house walls forms part of the 

 dam structure. With vertical units the turbines are always 

 located in a basement, the thrust bearing being supported on an 

 intermediate floor below the main floor, unless suspension bear- 

 ings are used, these being mounted on top of the upper generator 

 bearing bracket. 



Governors. The governors should be located on the generator 

 room floor close to the units which they are to control, and con- 

 nected to the operating cylinders on the turbines directly 

 below. The governor oil pumps with their pressure and storage 

 tanks should also be installed in the basement, and similarly 

 the oiling system for the turbo-generator units. 



Generators. The turbo-generator units are located on the 

 main floor and are almost always arranged in a line along the long 

 axis of the station (Fig. 90). They should be spaced far enough 

 apart so that ample space for passage is provided between them. 

 Horizontal sets may be installed either at right angles (Fig. 91) 

 or parallel (Fig. 92) to the long axis, the latter method being 

 necessary for high heads where impulse wheels are used. The 

 arrangement of the rest of the equipment, such as the trans- 

 formers, may also be a determining factor in regard to which 

 direction the sets should be installed. If one transformer bank, 

 consisting of single-phase units, is to be installed for each gen- 

 erator, the space occupied by them may be of such a length that 

 it would be more economical to install the turbo-generator sets 

 parallel to the long axis, thus reducing the width of the building. 

 Exciters. The exciters are, as a rule, installed on the same 

 floor as the main generators and in the center of the station. 

 The advantage of such an arrangement is that the exciters will be 

 located close to the operating switchboard, and the amount of 

 copper required for the exciter leads is thus a minimum. The 

 system may readily be sectionalized, one exciter serving the 

 generators located in one-half of the station, and the other the 

 generators on the opposite side. This does not, of course, refer 

 to direct-connected exciters or to individual motor-driven exciters, 

 which are located near their respective generators. 



Transformers. Due to their weight, the step-up transformers 

 should preferably be located on the main floor. They are gen- 

 erally installed in isolated compartments in the rear bay, sep- 



