Dynamic Thermal Line Loading Monitor

Operating a reliable and safe power transmission system is the goal of BPA. In doing so, BPA usually does not attain maximum transmission capacity due to continuous loading thermal limits placed on the transmission system. Thermal limit being the highest temperature at which a line conductor can be operated without violating minimum ground clearance criteria. However, lines do not instantaneously attain their thermal limits. The time it takes a conductor to reach its thermal limit can be used to BPA´s advantage (Figure 1). Instead of operating a transmission system to insure that a first contingency does not cause an overload condition, BPA can operate the system at higher current levels provided the conductor´s thermal response allows adequate time for manual intervention.