192 POWER-HOUSE DESIGN 



The switchboard containing the switches, etc., for the exciters 

 and other station auxiliaries, should be located on the main floor 

 at some convenient point, usually below the control-board gallery. 



Oil Circuit Breakers. The low-tension oil circuit breakers are 

 generally of the enclosed type and, together with the low-tension 

 busbars, are located in compartments on the main floor back of 

 the transformer compartments. The switches themselves should 

 preferably be set in parallel rows and opposite the generator and 

 transformer bank which they control, so as to call for as short a 

 connection as possible and in order that these connections may be 

 of equal length. The high-tension oil switches and busbars, and 

 also as a rule the lightning arrester tanks, are installed on the 

 floor above. 



Lightning Arresters. The aluminum arrester is now generally 

 usedjn all high-voltage stations. Both the arrester tanks and the 

 associated horn gaps may be located within the building, or the 

 horn gaps may be placed outside and the tanks inside, or both may 

 be placed outside, provided there is no danger of the electrolyte 

 freezing. Standard equipments of 27,000 volts and below are 

 usually designed as complete units to be installed inside the 

 station, whereas for those above 27,000 volts the horn gaps should 

 preferably be installed outside the station, although the tanks 

 may be inside. There is, however, a growing tendency to in- 

 stall the entire lightning arrester equipment outdoors for these 

 higher voltages. 



The arrester should naturally be placed close to the line en- 

 trances, and the location should also be such that the path for the 

 discharge from the line conductors to the arresters and ground 

 will be as straight as possible. When installed out of doors, it 

 may be placed on the roof of the building or on a separate struc- 

 ture at the side of the building. 



A number of modern station layouts illustrating some of the 

 numerous manners in which the apparatus may be arranged are 

 shown in Figs. 93 and 101. 



Outdoor Apparatus. With the introduction and successful 

 operation of the outdoor sub-station, this method of installing at 

 least part of the generating station apparatus outdoors should be 

 given careful consideration. A large installation of this kind is 

 that of the Utah Light and Power Company, where only the 

 generating and exciter units and the low-tension switching equip- 



