Discussion at annual convention

V. E. Thelin: The manually operated substations now in operation on railway systems in large cities offer a wonderful field for the use of automatic equipment, due to the fact that the line losses can be reduced considerably, schedule speeds increased, and in many cases sufficient copper can be taken down to pay for the cost of the land and new buildings as well as that of moving the machines. If the manually operated substations, which have a capacity of from 4000 to 20,000 kw., are redistributed into any number of single-unit or, at the most, two-unit automatically controlled substations, the service rendered by same no doubt will be far superior to that now obtained in the manually operated substations, due to the fact that each operation in the automatic substation has been worked out beforehand and the entire sequence is carried through without any hesitancy or error such as frequently happens to the operator in manually controlled stations. In the large manually operated substations with many units it is necessary to clear the board of practically all the feeder sections before the first rotary can be connected to the bus, whereas a single-unit automatic substation will have a maximum of say from five to eight feeders, and there should be no difficulty experienced in the station picking up all the sections simultaneously. It is possible, through the use of special devices which I have in mind, to isolate each substation district from all other districts, and by using automatic reclosing circuit breakers service can be restored quickly, whereas if all substations were tied together through bus lines the first station to be connected to the system would open up an overload through excess of load fed from the surrounding substation districts through the bus lines.