The Philadelphia A-C. Network System Development and Operation of a Network System Having Fused Secondary Mains and 2,300-Volt Loop Circuit Supply

The object of this paper is to outline the engineering plan of the low-voltage a-c. network system in Philadelphia, Pa. and to summarize operating experience over a five-year period. The development of this system and the operating experience will be of interest, since several basic features, which contribute toward the successful results, are different from the basic plan in other types of network systems. The system consists of sectionalized primary loop feeders, supplying a fused secondary network. At present there are twenty-four feeders in operation, with a total normal operating capacity of 32,540 kva.; the coincident feeder peak to date being 27,600 kva. The conclusions in the paper are essentially as follows: 1. The system plan initially adopted has been followed without fundamental change, and has proven amply flexible to meet changed load conditions as the area develops. 2. Operating experience has been very satisfactory, under all conditions, including those at time of faults on the network or else-where on the system.