Design and Experience With 4-Kv Primary Network Systems in the Washington Area

The 10 years of experience with the primary network upon the Potomac Electric Power Company system serving the metropolitan area of Washington, D. C., have resulted in the following conclusions: 1. A primary network system can be installed at a lower cost than new large radial 4-kv stations where load distribution is uniform and reserve facilities against loss of equipment would be supplied for the radial system. 2. Construction to supply new loads is simpler and more flexible with the primary network system, since it tends to avoid overhead wire congestion and the need for underground construction. 3. Operating reliability is improved. 4. Voltage regulation is improved. Since the start of the war period, the primary network system has grown from 25,000 to 106,000 kva. It was able to pick up large loads with only small increments of new materials during this period, and expected investment economies have been realized.