Standard Voltage A-C. Network

The object of this paper is to present a description of the Dallas (Texas) underground network system. This system is of interest since it is directly opposed to the general trend of furnishing non-standard voltages in underground systems. The reasons for its selection and its advantages over the three-phase four-wire system are presented. A brief description of the installation of equipment in vaults and manholes is given. Another feature of this system is the use of standard reactance transformers together with an external reactor, shunted by a fuse, for purposes of overload protection to the transformers. In addition to the regular network this system has a single-wire manhole and vault lighting network which is also used as a control wire for turning on and off multiple street lamps. Another feature of this system is a complete underground telephone system with a telephone outlet in each manhole and transformer vault. This telephone system is also connected to float switches in transformer vaults which automatically notify the trouble office in the event of high water in a transformer vault. The routine tests made in connection with the operation of the network system are described and the method of locating primary faults is given in detail. Complete records are kept of the installation of conduit and cable. Photographic records of construction, operation, and cable failures, etc., are also kept. The record of this network system both as to efficiency and as to continuity of service is excellent.