ABSTRACT
This chapter is in essence a continuation of Chapter 9’s discussion about engineering paradigms and methods. Here, the focus is on the distribution system. The power distribution system (primary feeder system) accomplishes more of the power delivery function in most electric utility systems than any other level of the system. Power is routed into a few locations in fairly large amounts, and the distribution system then routes and sub-divides that power into smaller allotments delivered to many different locations. No other layer of the power system accomplishes so much dispersion over area or so much sub-division of power from large to small. The primary distribution level also has more impact on customer power quality than any other layer. It is both immediately downstream of the lowest-level voltage regulation equipment in the system (substation voltage regulators or load-tap changers), and by the nature of its topography, the source of the majority of voltage drop that the customer sees. That topography also means that the majority of outages that the customer sees are caused by the distribution system – there are simply more miles of exposed line at jeopardy to weather, accident, and random failure. Thus, in most systems, the distribution system is the source of the majority of both the voltage-related and availability-related power quality problems seen by energy consumers.
