voltage drop in acsr #2 calc 3

[maxPE]

In discussions with the county engineer, he suggested that I could design my line myself and stamp it. P.E.ME ...as long as the calcs were reasonable. I may be over my head here but his big issue seemed to be the the voltage loss in ACSR 2 over a 9000 foot run at 4160 3 phase. The load is 26 kw. Intuitively it seems a no brainer to me since I have run #4 cu underground at 50 amps over 1500 feet with a marginally acceptable drop. The voltage drop at 4160 and 26kw seems to be minimal to me but he seemed to have difficulty with the significance. I cannot believe that surfing the net I cannot seem to locate a chart showing drop per amp-foot for ACSR #2 cable! I have used charts for standard copper before and they seem easy to locate. Any ideas? Am I missing something important as the county engineer implied?

 

[jbartos]

Comment: The voltage drop will somewhat depend on the ACSR #2 transmission line configuration.
Westinghouse Electrical Transmission and Distribution Reference Book includes for ACSR 2 in Table 2-A:
180A = Approximate current carrying capacity amps
1.41 = Resistance in Ohms per Conductor per Mile at 77degF Small Currents
1.69 = Resistance in Ohms per Conductor per Mile at 122degF
.592 = Inductive Reactance Ohms per Conductor per Mile at 1Ft spacing, Small Currents
.665 = Inductive Reactance Ohms per Conductor per Mile at 1Ft spacing, Current Approximately 75% capacity
0.1285 = Shunt Capacitive Reactance Megohms per Conductor per Mile at 1Ft spacing

 

[alehman]

To follow up on the previous post, the reactance spacing facotr must be added to the reactance at 1ft. The quoted reference includes a table of spacing factors.

3ft - 0.1333
4ft - 0.1682
5ft - 0.1953

Or the reactance can be calculated directly-

X = 0.004657 * f * log (Deq/Ds) ohms/mile

where
Deq is the GMD between condcutors
= cube root(Dab*Dbc*Dca) (ft)
Ds is the self-GMD
for seven strand cable = 0.4114 sqrt(A) * 12/1000
where A is the cross-sectional area in cm

 

[jghrist]

See

http://www.usace.army.mil/publications/armytm/tm5-811-1/chap5.pdf

for voltage drop calculations, typical voltage drop allocations, and a table of load values that includes #2 ACSR 4160 volts.