## Wednesday, 15 April 2015

### PSU voltage drop on feeder cable to rig

Just posted to Elecraft list... so in case asked:

## HOW TO CALCULATE VOLTAGE DROP AND ENERGY LOSSES IN A WIRE?

### VOLTAGE DROP

Voltage drop is given by the following formula : Where :

U : Voltage of the DC or AC system (V)
NB: for DC voltage drop in photovoltaic system, the voltage of the system is U = Umpp of one panel x number of panels in a serie.
ΔU : voltage drop in Volt (V)
b : lenght cable factor, b=2 for single phase wiring, b=1 for three-phased wiring.
ρ1 : resistivity of the material conductor, 0.023 for copper and 0.037 for aluminium (ambiant temperature = 25°C) in ohm.mm²/m.
L : simple lenght of the cable (distance between the source and the appliance), in meters (m).
S : cross section of the cable in mm²
Cos φ : power factor, Cos φ = 1 for pure resistive load, Cos φ< 1 for inductive charge, (usually 0.8).
λ : reactance per lenght unit (default value 0.00008 ohm/m)
Sin φ : sinus (acos(cos φ)).
Ib : current in Ampere (A)

NB : For DC circuit, cos φ=1, so sin φ=0.

Voltage drop in percent :
ΔU(%) = 100 x ΔU/U0
Where :

ΔU : voltage drop in V
U0 : voltage between phase and neutral (example : 230 V in 3-phase 400 V system)