Voltage Drop Formula
Voltage Drop Formula
(OP)
I'm a fairly new engineer working for the local power company. I have been tasked with sizing an underground run for a mobile substation. Unfortunately, I didn't have any power courses in college, so I have spent some time researching equations. Can anyone provide a website or an equation to use to calculate Voltage Drop. I have found some equations on-line, but would like to verify I'm doing things correctly. Some information follows:
Size of mobile transformer- 35 MVA
2 conductors per phase
Conductor size- 500 kcmil, triplex
1 run of triplex in 6 inch conduit (second run of triplex in another 6 inch conduit)
I appreciate everyones' response.
Thanks
Size of mobile transformer- 35 MVA
2 conductors per phase
Conductor size- 500 kcmil, triplex
1 run of triplex in 6 inch conduit (second run of triplex in another 6 inch conduit)
I appreciate everyones' response.
Thanks






RE: Voltage Drop Formula
%VD= (KxIxZxLx100)/V
K=Phase Coefficient (2 for single phase circuit or 1.73 for three phase circuit)
I=Full Load Current (Ampere)
Z=Impedance of copper conductor(Ohms/meter)
L=Single length of conductor (Meters)
V=Source voltage at switchboard or transformer secondary (Volts)
RE: Voltage Drop Formula
Try the voltage drop Excel spreadsheet at:
ht
Mike Holt is well respected so I assume it is correct. I have not used it myself though. Hope it helps.
RE: Voltage Drop Formula
The formula used appears to be based on resistance only.
You should be aware that there may be additional voltage drop due to inductive reactance. Inductive reactance is a function of both conductor size and spacing. It would probably be negligible for short runs of triplex, particularaly as the voltage rises. It is significant in longer runs of overhead lines.
Is this a 34500 volt circuit?
respectfully
RE: Voltage Drop Formula
RE: Voltage Drop Formula
RE: Voltage Drop Formula
htt
http://www.skm.com/support/kb/120000.pdf
RE: Voltage Drop Formula