Abstract :
This paper describes a two-unit automatic station which supplies power to a 3-wire, 250-volt, d-c. Edison network. It covers a general description of the machines and of some of the devices, of the scheme of automatic operation employed in controlling these machines, and of the method of protecting against emergency conditions. Although the paper itself deals with this specific installation only, the fundamentals involved are the same for the general class of equipments employed in this service. However, there are generally certain important differences caused by special operating requirements of the individual installation or system. The character of the load determines whether the station is to be in service continuously, or is to be placed in service in response to load demand, by remote control or by some other means. The capacity and regulation of the a-c. system determine whether Y-delta, compensator or reactor starting is to be employed. The location of the station with respect to the load and the layout of the d-c. system determine whether only one bus, or both high and low-voltage buses are required. These and other factors must be taken into consideration so that the equipment will meet the requirements of the individual installation or system. Hence, each installation is to a certain extent its own problem, for it must maintain the required character of service under all conditions no matter what special operating requirements are present.
