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voltage drop in acsr #2 calc
3

voltage drop in acsr #2 calc

voltage drop in acsr #2 calc

(OP)
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?

RE: voltage drop in acsr #2 calc

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

RE: voltage drop in acsr #2 calc

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

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