Voltage Drop Equation

Sure, the laws you should learn are Ohm's law, Kirchoff's mesh and nodal analysis, and the rules of super position. It would also be very useful to know how to do a Laplace transform. This will be much easier than doing the differential calculus but it all depends on your mathematics background which method will be easier. It would also help if you have an understanding in linear algebra and matrix equations but one can get away with just simple algebra. If you feel really ambitious you could look into Oliver Heaviside's work on transmission line equations.

Sorry Fred you forgot the Henweigh equation.

OK, here goes.

What's a Henweigh?

Sorry

That just never gets old!

^{Maybe it gets a little old...}

Bad

The guys are kidding with you but you question is vague. Do you understand the difference between single and three phase installation and loads? Do you have a particular equation that you are referring to? Come back as see if you can add something to the discussion.

And

Lyn you are bad but you make me laugh. You are instant insanity.

I wasn't joking. If badhabbitrabbit can get a solid grasp of the half dozen equations and analysis techniques I proposed then he'll definitely be ready to handle any voltage drop equations, regardless of the number of phases. It took me a few years of schooling and application for me to claim a passable grasp of these, but who knows what this rabbit is capable of doing.

VD=k*(Rcosθ+Xsinθ)*I*L..

where: k=1.73 for three phase, 2 for single phase and DC source

R=ac resistance of wire in ohms/km

cosθ=power factor of the load to be supplied

sinθ=reactive factor=sqrt[1-(cosθ)ˆ2]

I=line current of the load

L=length of the cable in km..

just be careful with the units...