Distribution System Maintenance (PECO)

Distribution System Maintenance

A distribution system is made up of several components including lines or conductors, poles, transformers, substations, switches, circuit breakers, fuses and lightening arrestors. The lines carry power from substations and deliver it to homes, businesses, and other customers. If there is a problem with electric facilities, service can be interrupted to a single customer, a group, or as many as a few thousand customers.

PECO works to minimize these outages through constant system monitoring, regular maintenance, and upgrades for performance improvement. These programs help maintain safe, reliable service along 21,227 miles of electric distribution lines. The programs include:

• Vegetation Management: PECO typically prunes or clears tree limbs that can affect overhead wires and cause power outages. In some cases, “hazardous” or unhealthy trees or fast-growing invasive trees are removed rather than pruned. PECO uses industry-best management practices for tree clearance around utility facilities. This method is known as directional or natural target pruning. It is designed to guide the growth of trees away from the distribution wires while preserving the health of the tree.
• Circuit Patrols: The entire overhead portion of the system is visually inspected from the substation to a customer’s service line on an annual cycle. (Note: We just changed to an annual cycle for 2009, but the frequency is currently being debated.) The patrol includes a driving and walking inspection of the primary line, all lateral taps, as well as other utility equipment.
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• Top Priority Circuit: This program is designed to improve local circuit performance to reduce the number of sustained interruptions and improve customer satisfaction. The top priority circuit program addresses underperforming distribution circuits. PECO analyzes and prioritizes upgrades on the worst performing circuits each year.
• Distribution Automation: This program involves the installation of equipment that automatically reconfigures delivery of power in outage situations. Switches, sectionalizers, and reclosers are used to detect and isolate problems to minimize the number of customers that may be affected by an outage. These devices can also prevent extended outages for customers when a “fault” occurs.
• Device Frequency Program: This program is designed to identify specific equipment, such as fuses or breakers that have been associated with multiple power outages in the past year.
• Customer Target Program: This program is designed to identify specific customers that experience a higher than average number of power outages, regardless of where or how the outage occurred. Engineers track reliability performance, identify improvements, and design customer-specific solutions.
• Thermography: Thermography is a preventive maintenance tool that, with the use of an infrared camera, identifies potential equipment problems prior to failures that affect customers. The camera records temperature variations with equipment in operation, and the analysis of these thermal images triggers the scheduling of corrective maintenance.