Great slides, very useful, thanks. My questions are: any longer-term data on longevity? Any forensic studies of line failure with ACCC? What is the differential price?
Overall this appears to be a good strategy to increase the capacity of existing utility power transmission lines. Here are my comments. Manufactures of all aluminum conductors and ACSR (Aluminums Conductors Steel Reinforced) provide the amount of current for the different kcmil sizes the conductors can carry that raises the conductor temperature up to 75 degrees C when the ambient air temperature is 25 degrees C and the wind is blowing at 2 km/hr or2 ft/sec. Note that all aluminum conductors are only used for distribution and not for transmission since for distribution the spans are much shorter and the extra strength provided by ACSR is not required. With the same ambient conditions, higher currents can be carried with higher conductor temperatures. Also, the colder the air temperature and the faster the wind speed, the higher amount of current the conductor can carry with the conductor temperature remaining at 75 degrees C. The higher the temperature of the conductor, the higher the resistance and the more sag it will have. The tensile strength also decreases with higher temperature but up to about 200 degrees C it is not significant especially for aluminum alloys. For ACCC conductor, In addition to current ratings for conductor temperature at 75 degrees C, the manufacture also provides current rating for conductor temperatures ot 180 C and 200 C also with ambient air temperature at 25 degrees C and wind speed at 2 km/hr or2 ft/sec. The increase in sag for ACSR conductors can be significant when higher currents increase conductor temperatures, whereas for ACCC the sag is much less for the higher temperatures. Resistance also increases considerably when higher currents increase conductor temperature, which is true for both ACSR and ACCC. Increasing conductor temperature from 75C to 150C increases the resistance of aluminum by about 29% and going from 150C to 200C will increase resistance by another 15% for a total increase of about 48% when temperature is increased from 75C to 200C. Since the same size ACCC conductors or lighter than ACSR conductors, ACSR can be replaced with about a 30% larger size ACCC conductor using the same towers that support them. This means that for the same amount of power being transmitted, the ACCC conductors will have lower heat losses. In addition to ACCC being able to carry more current because it is replacing a smaller size ACSR conductor, ACCC conductors can also be operated at higher temperatures because they will have less sag at higher temperatures than ACSR. If a conductor can be operated at higher temperatures, it can also carry more current but resistance also increases. Increased resistance results in a higher percentage of power going into heat losses. Doubling the current, hence doubling the power, increases the conductor temperature from 75C to 200C which will increase the resistance by 48%.. If conductor power lost to heat are in the 5% range when conductor temperature is at 75C, the power lost to heat will increase to about 7.4% range when the temperature is at 200C Because the reactance of a transmission line is over twice as much as the resistance, even if the resistance is increased by 50% at the higher temperatures, the impedance, which is the square root of the reactance squared plus the resistance square, will only increase by a few percentage points. This means that the higher resistance values at the higher temperatures will not have much effect on voltage drop. Voltage drop is the current multiplied by the conductor impedance so the increased current will have much more of an effect on voltage drop than impedance will because the current would have increased a lot more than the impedance when the conductor is at 200C.
Great slides, very useful, thanks. My questions are: any longer-term data on longevity? Any forensic studies of line failure with ACCC? What is the differential price?
Overall this appears to be a good strategy to increase the capacity of existing utility power transmission lines. Here are my comments.
Manufactures of all aluminum conductors and ACSR (Aluminums Conductors Steel Reinforced) provide the amount of current for the different kcmil sizes the conductors can carry that raises the conductor temperature up to 75 degrees C when the ambient air temperature is 25 degrees C and the wind is blowing at 2 km/hr or2 ft/sec. Note that all aluminum conductors are only used for distribution and not for transmission since for distribution the spans are much shorter and the extra strength provided by ACSR is not required.
With the same ambient conditions, higher currents can be carried with higher conductor temperatures. Also, the colder the air temperature and the faster the wind speed, the higher amount of current the conductor can carry with the conductor temperature remaining at 75 degrees C.
The higher the temperature of the conductor, the higher the resistance and the more sag it will have. The tensile strength also decreases with higher temperature but up to about 200 degrees C it is not significant especially for aluminum alloys.
For ACCC conductor, In addition to current ratings for conductor temperature at 75 degrees C, the manufacture also provides current rating for conductor temperatures ot 180 C and 200 C also with ambient air temperature at 25 degrees C and wind speed at 2 km/hr or2 ft/sec.
The increase in sag for ACSR conductors can be significant when higher currents increase conductor temperatures, whereas for ACCC the sag is much less for the higher temperatures. Resistance also increases considerably when higher currents increase conductor temperature, which is true for both ACSR and ACCC. Increasing conductor temperature from 75C to 150C increases the resistance of aluminum by about 29% and going from 150C to 200C will increase resistance by another 15% for a total increase of about 48% when temperature is increased from 75C to 200C.
Since the same size ACCC conductors or lighter than ACSR conductors, ACSR can be replaced with about a 30% larger size ACCC conductor using the same towers that support them. This means that for the same amount of power being transmitted, the ACCC conductors will have lower heat losses.
In addition to ACCC being able to carry more current because it is replacing a smaller size ACSR conductor, ACCC conductors can also be operated at higher temperatures because they will have less sag at higher temperatures than ACSR. If a conductor can be operated at higher temperatures, it can also carry more current but resistance also increases. Increased resistance results in a higher percentage of power going into heat losses. Doubling the current, hence doubling the power, increases the conductor temperature from 75C to 200C which will increase the resistance by 48%.. If conductor power lost to heat are in the 5% range when conductor temperature is at 75C, the power lost to heat will increase to about 7.4% range when the temperature is at 200C
Because the reactance of a transmission line is over twice as much as the resistance, even if the resistance is increased by 50% at the higher temperatures, the impedance, which is the square root of the reactance squared plus the resistance square, will only increase by a few percentage points. This means that the higher resistance values at the higher temperatures will not have much effect on voltage drop. Voltage drop is the current multiplied by the conductor impedance so the increased current will have much more of an effect on voltage drop than impedance will because the current would have increased a lot more than the impedance when the conductor is at 200C.
Any ACCC advantage with resistance to EMP?