Sixing of ACSR Over Head Conductor

There are published tables, but most lines are sized well above minimum size necessary to handle the fault current. A line that won't carry load isn't of much use.

I'm with davidbeach. No need for re-inventing the load current tables that have served us for so long.

Good on ya,

Goober Dave

I would agree with the 2 Daves. I've never seen fault current being the limiting factor in sizing ACSR conductor. Economics should be the main factor, and my experience is that sizing so the peak load is about 1/3 the ampacity is generally close.

The formula mentioned above is applicable to determine the capability of the conductor to withstand a short circuit current.

For ACSR conductor a value of K=0.0862 may be used

[sub]Where:
I = curren (amperes)
S = cross sectional area of conductor (cmil)
t = clearing time(sec) for t up to 1 sec.

This is based considering a melting temperature for aluminum of 645 degress C and assuming the steel (1084C)of the ACSR will be not significantly affected since most current will be carried by the aluminum outer conductor.[/sub]

The procedure outline on the IEEE Std 738 could be used for calculating the ACSR conductor sizing for steady state current.

I would be concerned about taps that feed just a few customers. However having said that, the proper protection of those taps should be consitered.
There are devices, like fault tamers, that can limit fault currents.

But in general, main lines should not have problems like this (I guess you can fix them if they do).

I've also seen this problem on tie's that are rarely used. No one thought to fix them over the years, and because they were rarely used, no problems were seen.

This is the tradeoff between low impedance-low loss Stepdown transformers, and higher impedance/higher loss stepdown transformers. It just seems to cost something somewere.