Software for the air conditioning, ventilation and refrigeration industry
No burnouts allowed
This program does electrical cable sizing, based on the most basic electrical laws.
If you are planning to do cable sizing for a real installation, check the results and make sure that you comply with all electrical regulations.
From Ohms law, the voltage drop in an electrical conductor is
V = I R
I = Current, amps
R = Resistance, Ohms
The electrical resistance can be derived from the properties of the conductor material.
R = ρ L / A
ρ = Resistivity, Ω mm2 /m
L = Length, m
A = Cross sectional area, mm2
Watch the units in the above equation.
The resistance can also be expressed in terms of the material conductivity (ψ) which is just the reciprocal of the resistivity.
R = L / (ψ A)
Combining Ohms law with the resistance expression, we get.
V = (I L) / (ψ A)
Now, we can define an acceptable voltage drop in a conductor. I have calculated the voltage drop that was used in several published tables and get around 5.5 Volts.
We could therefore re-arrange this equation to give the cable size. But cables come in standard sizes measured in mm2. In addition, you also need to consider the maximum current for each cable size.
So, the theory is relatively simple, let us now see how to use the program.
Enter the following and the program calculates line current and cable area.
The normal voltage drop is based on 5.5 Volts. You can edit this value if necessary by pressing the [Settings] button.
Electrical heating loads up to 84 kW
Single phase motors up to 5.5 kW
Three phase motors up to 110 kW