Electric Distribution Feeder Backbone Protection

Analyses of electric distribution systems repeatedly verify that the most immediate and cost-effective strategy for improving an electric utility’s distribution circuit reliability is protection of  the feeder backbone. The feeder backbone, also referred to as the mainline, main gut, or feeder (though the latter term sometimes refers to the whole circuit), is usually the three-phase part of...

Service Restoration in Storm Conditions

Some of the major insights of leading electric utilities regarding service restoration in storm conditions is the considerable benefit that can accrue to early mobilization of field personnel. Although these benefits must be weighed against the cost of mobilizing resources for a “false alarm” (e.g. a storm that does not hit or does less damage than that forecast), the pendulum is swinging...

Grid Modernization- The Path to Full Network Automation

Current priorities placed on Advanced Metering Infrastructure (AMI) and SmartGrid technologies at the highes levels of state and federal government are creating compelling pressure on every utility to commit significant investment to such initiatives. But the path to success involves a plan that integrates myriad of factors, including: Electric Grid Modernization Broad array of developed and...

Distribution System Capacity Planning and Overload Forecasting

Distribution System Capacity Planning can be viewed as a four-stage process, as depicted in Figure 1 below: Forecast Load The load forecasting phase of the capacity planning process addresses those activities that allow planners to predict with a reasonable degree of accuracy the demand for electricity in a given area as well as for each distribution circuit. These forecasts account for both...

Pre-Mobilization for Storm Response

To the extent that an electric utility properly pre-mobilizes for an upcoming storm, the response and restoration times will be significantly improved. There are, however, additional practices and processes that should be incorporated into an overall storm mobilization strategy. The prediction and assessment of damage, assignment of appropriate personnel (experience and quantity) and estimate of...

Animal Guarding and Impact on Electric System Reliability

The most common example of an animal-caused service outage involves a squirrel and less frequently involves a bird, raccoon or snake. The figure nearby illustrates a typical example of a squirrel sitting on the top of a transformer  tank (which is grounded) and making contact with the primary lead above the bushing (or sometimes through the lighting arrester attached to the tank). Other less...

Enhanced Vegetation Management-Impact on Electric System Reliability

Electric Utilities typically evolve through three stages with respect to vegetation management (commonly referred to as tree trimming): Get on Cycle Tree trimming specifications normally establish a periodic (commonly a four- or five year) cycle to ensure proper clearances are maintained between vegetation and electric distribution lines. However, electric utilities have commonly deferred tree...

Underground Residential Distribution (URD) Cable Replacement

The electric utility industry in the United States grew significantly the 1960s and 1970s (Refer to Figure 1) and this led to the installation of a large number of electric utility plant assets for generation, transmission, and distribution. Figure 1: U.S. Growth Trend - URD Cable Installation in the US 1960 - 2005 Concurrent with this spike in growth, suburban locations nationwide desired the...

Distribution Pole Inspections and the Impact on Electric System Reliability

Frequency and Process of Wood Pole Inspection The typical wood pole inspection program involves inspecting 10 percent of an electric utility’s poles in a given year (i.e., poles are inspected on a ten-year cycle). These inspections are conducted using utility personnel or more commonly a specialty service contractor. Some inspection programs are the result of mandated programs in some...

Introduction to Plug-in Hybrid Vehicles (PHEVs)

What are PHEVs? Plug-in hybrid electric vehicles (PHEVs) are passenger vehicles that combine both an internal combustion engine (ICE) and a battery-powered electric motor of an electric vehicle (EV).     PHEVs operate at the outset of any trip on the electric power stored in their battery. When this power is exhausted, they convert to their ICE mode for the balance of the trip. PHEVs are...