The output from generators and dynamos is regulated by means of switches on a switchboard (Fig. 9) which is divided into two sections: the machine panels, and the feeder panels. The machine panels are equipped with ammeters, with the switches necessary for regulating, and with voltmeters for measuring the electrical energy generated. The feeder panels have similar instruments for controlling the output of energy to the various circuits. The operator in charge of the switchboard is able to tell by a glance at these instruments the amount of work each machine is doing, and thereby to know when it is advisable to throw out of or put into operation additional machines. A rheostat is furnished for each generator so that the pressure may be varied. Circuit-breakers or fuses to interrupt any particular circuit through which an excessive current may flow, are also included in the switchboard equipment.
Fig. 93. - A Switchboard.
A switchboard is always placed away from the wall or ceiling to reduce the danger of communicating fire to adjacent combustible material. Conductors should be of soft annealed copper, about 97% pure, and should be insulated for their entire length by a vulcanized rubber compound that adheres to the wire. Wires should be arranged to secure distribution centers in easily accessible places so that cutouts and switches may be conveniently located. The load should be divided as evenly as possible among all the branches, and complicated and unnecessary wiring should be avoided.