The Fundamental Plan of Power Supply of the Detroit Edison Company

Experience indicates that if electric light and power systems are to expand indefinitely without enormous obsolescence charges a carefully coordinated engineering plan must be adopted and, as far as practicable, system extensions fitted to it. This paper sets forth the principles involved and the plan adopted by the Detroit Edison Company. The description of the area served and the classification of customers indicates that the system is essentially of the metropolitan substation type supplemented by a 120-kv. transmission system. The importance of selecting proper circuit voltages and arrangements and their bearing on service reliability, system simplicity, and cost is discussed. The underlying principles and the ``Loose Linked´´ Power Area Plan adopted to accomplish those principles is set forth. This is supplemented by the plan for short circuit and stability control and the resultant classification of substations, power sources, and protection schemes. Those characteristics of major electrical equipment affected by the plan are outlined. Operating procedure and results are given.