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Diagrams of Boards in Actual Service.
In the foregoing sections we have explained the way in which switchboards are connected for single generator and multiple generator plants, and also for the three-wire system. The diagrams given are imaginary, with the exception of Fig. 18, and are so arranged as to present the subject in the clearest light, and also so as to indicate as far as possible the modifications required to meet given conditions. In this chapter we will give the diagrams of connections of boards in actual service, and thus show the requirements that have to be met in actual practice, and also the way in which they are met by different designers.
Fig. 25 is a diagrammatic view of the switchboard of the Crescent Steel Works, Pittsburg, Pa. It is arranged to connect two generators of a capacity of 1,000 amperes each and 250 volts electromotive force so as to distribute into a system of circuits, twelve of which are controlled directly and independently from the board, the others being also controlled from the board, but not independently. The two generator circuits and the twelve distributing circuits are provided with magnetic circuit breakers, which also act as switches. These circuit breakers are of the twopole independent action type. They are called two-pole because they open the circuit on both sides; thus if the circuit breaker directly above the left-hand generator is opened it will break the connection between the board and the two wires running to the generator, one to the left side