AUXILIARY APPARATUS 427 



Switchboards for large alternating-current stations 

 are different from that shown above. The bus-bars of an 

 a-c. switchboard are generally of high voltage, perhaps, 

 11,000 volts. The circuit breakers and switches must 

 be of the oil immersed type and are cumbersome and diffi- 

 cult to arrange well on the back of a switchboard. As the 

 oil switches are generally motor operated, it is of no advan- 

 tage to have them at the switchboard, so they are generally 

 located in some fire-proof recess out of the way. 



The control of these motor-operated switches is carried 

 to the master switchboard, generally quite small compared 

 to the main switchboard. From this master control board, 

 the chief operator can manipulate all the machines and 

 switches in the station. The master control board is 

 generally located in a quiet part of the station but is so 

 placed that the operator has in full view, all of the machines 

 and apparatus which he controls. The chief advantage 

 of the remote control switchboard rests in the possibility 

 of one operator carrying out all the necessary switching 

 in the station; the responsibility is thus centralized and 

 fewer accidents, due to improper switching, take place 

 than in a station where several operators are required. 



Another advantage is due to the isolation of the control 

 board; if an accident occurs in the station the chief operator 

 can carry out the proper switching operations without being 

 influenced by the confusion and noise in the generator 

 room. Small signal lamps of different colors, show the 

 operator what machines are running, what feeders are alive, 

 what switches are open, etc. In fact the operation of the 

 whole station is clearly shown and easily carried out by one 

 man working on the master control board. 



