TRANSMISSION LINE UPRATING FEASIBILITY ISSUES BASIC AND TUTORIALS

Technical Feasibility. For this kind of analysis it is important to consider at least the following points:

• System load requirements. It is important to evaluate for how long the uprated/upgraded line will satisfy the load requirements.

• Assessment of current conditions and life expectancy of transmission line materials. It is important to make this kind of evaluation for the main transmission line components, such as towers, foundations, conductors, insulators, and hardware.

• Potential margins for uprating/upgrading. It is important to check electrical clearances, mechanical strengths, ROW width, as well as the possibility of compliance with the requirements of safety codes (e.g., NESC), regulatory bodies and government agencies (e.g., navigable streams, public lands, air lanes).

• Utility considerations. Sometimes electric utilities are not authorized to take the transmission line out of service to perform the necessary uprate/upgrade services. In these cases it is important to check if the mentioned services can be done with the line in service.

Economical/Financial Feasibility. For this kind of analysis it is important to consider at least the following points:

• Uprating/upgrading costs vs. new line costs. It is important to remember that technical analysis of old lines usually requires data gathering and this can be very expensive and time consuming.

Besides that, it is necessary to estimate what will be the need of the uprated line in terms of additional ROW. Other costs that can be relevant are related to construction (material and labor), maintenance and operation of the uprated line. Environmental costs are usually higher for new lines.

• Uprating/upgrading costs vs. uprating/upgrading benefits. Environmental Feasibility. For this kind of analysis it is important to consider at least the following
points:
• Environmental considerations. Usually not so critical when compared to new lines. However, it may be necessary to deal with historical societies, environmental groups, concerned neighbors, and so forth.

• Right-of-way easements. If significant changes will be made to the original line, it is necessary to check the validity of the previous ROW terms of use. It can be difficult to get licensing for the modified line. It is also important to check the existence of ROW encroachments and line crossings that would be unacceptable by the uprated line.