VOLTAGE DROP CALCULATION

[ilong]

GOOD DAY GUYS..

I AM CALCULATING VOLTAGE DROP FOR OUR PROJECT..BUT I AM CONFUSE WHAT FORMULA AND HOW TO CALCULATE THE VOLTAGE DROP OF OUR CABLE 4C 25MM2 (380/220V)...CAN YOU GIVE ME THE FORMULA AND EXAMPLE HOW TO CALCULATE..OUR LOAD IS A LIGHTING FIXTURE 400W hps....

 

[luckylerado]

The formula that you want is as follows

(2*K*D*I)/cm for single phase and (1.73*K*D*I)/cm for 3 phase

k is the resistivity constant. use 12.9 for copper and 21.2 for aluminum.
D is your distance in feet from source to load.
I is the max current draw.
cm is the circular mills found in the conductor properties table.

This formula will give you the amount of voltage drop. Subtract from the source voltage to find the voltage at the load. Divide by source voltage and multiply by 100 to find the percentage.

This formula assumes an average ambient. Extreme ambient temperatures will skew the measured voltage drop.

 

[augie47]

You might find this calculator from Mike's "Free Stuff" handy:

http://www.mikeholt.com/documents/freestuff/other/VoltageDropCalculator.xls

 

[charlie b]

Please turn off the ALL CAPS feature. It is considered impolite, as though you were SHOUTING at us.