AUXILIARY APPARATUS 425 



streaks of conducting mineral matter through it) and is 

 much finer in appearance; of course it costs more than slate. 

 The panels may be from 18" to 24" wide and perhaps 6' 

 high. They are supported by a frame work of structural 

 steel anchored to the floor and wall of the station house. 



Bus-bars. Behind the whole length of the switchboard 

 run a set (two or three) of heavy copper bars, called bus- 

 bars, or sometimes merely busses. The general arrange- 

 ment of the board is to have all the generator panels on one 

 side and the feeder panels on the other; the bus-bars then 

 convey the total power of the station lengthwise along the 

 board. For this reason they have a very large cross-section. 

 They, as also the rest of the connecting bars and wiring 

 on the back of the board, are supported by porcelain chan- 

 nels and cleats fastened to the steel frame work of the 

 bo.'ird. 



Arrangement of Panels. Each generator is connected 

 through its respective circuit-breaker, ammeter, and switch 

 to the bus-bar at a generator panel and each feeder is con- 

 nected to the bus-bars through its ammeter, circuit breaker 

 and switch. By having all generator panels on one end 

 of the board and all feeders on the other end, the addition 

 of more generators or feeders is easily accomplished with- 

 out disturbing the arrangement of the board; the proper 

 number of panels may be added at either end of the board. 



At the center of the board between the generator and 

 feeder panels is located the station output panel on which 

 are located the recording and watt-hour meters that show the 

 total power output of the station. By daily records of 

 these meters and of the records of the customers' meters, 

 the station manager may obtain an idea of the efficiency 

 of his system, i.e., the ratio of the amount of power sold to 

 customers to the total power sent out of the station. ^ 

 this ratio is low he must improve it by better insulation 

 of the outside lines, checking the accuracy of the customers' 

 meters, etc. 



