SWITCHING EQUIPMENT 535 



and potential receptacles could not all be accommodated in a 

 position most convenient for the operator. To overcome these 

 difficulties the benchboard has been introduced. In this manner 

 the useful surface has been increased by an amount almost equal 

 to the top of the bench, the latter offering an excellent position for 

 control apparatus, bringing it within distinct view and convenient 

 reach of the operator. 



Another advantage is also incidentally obtained by reason of 

 the greater distances between the instruments and the operator, 

 which enables him to observe a greater number of instruments 

 from any point while manipulating the control apparatus. A 

 further advantage may be taken of this condition by increasing 

 the height of the instrument section, if desirable, in order to 

 allow room for more instruments, which may be read without 

 difficulty. 



Figs. 338 to 341 show different types of bench boards in use 

 and the relative locations of the different pieces of apparatus. 

 Which type should be used depends entirely upon the apparatus 

 involved and on the local conditions. It is thus often found that 

 a bench board of a certain design will give the best result for con- 

 trolling the machines, while a vertical panel board will be more 

 feasible for feeder circuits. When separating the boards the 

 number of operators required should always be considered. 



Pedestal control boards are occasionally used, but there seems 

 to be no real advantage in splitting up the equipment to such an 

 extent. Figs. 342 and 343 illustrate two typical bench board 

 designs, and Fig. 344 shows the control room of the Mississippi 

 River Power Company at Keokuk. The operation in this sta- 

 tion is completely controlled by a chief dispatcher, who is in tele- 

 phonic communication with all parts of the system. A special 

 desk is provided for him, on which is mounted the telephone 

 switchboard, while, in front of this desk a miniature arc-shaped 

 switchboard is installed which contains a set of mimic bus-bars 

 showing by means of small indicating lights the open or closed 

 position of all the breakers in the station. It also contains 

 graphic voltmeters and ammeters for recording the voltage on 

 each bus section and the current in each of the outgoing lines. 



The main control switchboard is divided into sections corre- 

 sponding to the bus sections, with an additional section for the 

 auxiliary equipment. The arrangement of these boards is at 



