Maximum operating temprature of ACSR

[mbrooke]

What is the maximum operating temperature of ACSR before damage, creep or none elastic deformation occurs?


https://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet16


Apathetic of sag, the continuous operating limit I frequently see 140*C with 200*C reserved for short time emergencies. Second why does the Southwire chart calculate amps at 75*C when loss of strength does not occur above 100*C?

 

[drcampbell]

A popular rule of thumb says that metals do not soften at temperatures up to half of their melting point, measured on an absolute scale.
Depending on the alloy, steels melt at about 1700-1800 K, so that would suggest that they're mechanically sound at up to 850-900 K. (~600°C)

Aluminum melts at about 900K, so it's likely to begin softening (and the connections begin loosening) at about 450 K. (180°C)

I suspect that 75°C is used because it's typical of actual use, that being a compromise between the first cost and the ongoing cost of I²R losses, acceptable sag and acceptable voltage drop.

 

[K8MHZ]

A popular rule of thumb says that metals do not soften at temperatures up to half of their melting point, measured on an absolute scale.
Depending on the alloy, steels melt at about 1700-1800 K, so that would suggest that they're mechanically sound at up to 850-900 K. (~600°C)

Aluminum melts at about 900K, so it's likely to begin softening (and the connections begin loosening) at about 450 K. (180°C)

I suspect that 75°C is used because it's typical of actual use, that being a compromise between the first cost and the ongoing cost of I²R losses, acceptable sag and acceptable voltage drop.

I would not use that rule of thumb. Some metals become plastic at temperatures much lower than their melting point, others don't. Aluminum, for instance, is used in cooking at temps above 180 C, which is only 356 F and melts only a few degrees above the plastic phase which is much higher than 350 degrees. You can easily see the difference in solder. Eutectic solder goes from solid to liquid with practically no plastic phase, while standard 60/40 has a definite plastic phase.

 

[mbrooke]

A popular rule of thumb says that metals do not soften at temperatures up to half of their melting point, measured on an absolute scale.
Depending on the alloy, steels melt at about 1700-1800 K, so that would suggest that they're mechanically sound at up to 850-900 K. (~600°C)

Aluminum melts at about 900K, so it's likely to begin softening (and the connections begin loosening) at about 450 K. (180°C)

I suspect that 75°C is used because it's typical of actual use, that being a compromise between the first cost and the ongoing cost of I²R losses, acceptable sag and acceptable voltage drop.

If this forum had a like button, I would push it :thumbsup: I'd say you are spot on. 180*C seems to be the maximum continuous temperature most that most conductor software "recommends". 75*C is a bit low when paired with the real world, but 100-140*C is often the max continuous target so it would make sense keeping it below 180*C while maximizing use vs sag/loss/ect.