Line impedance calculations
Line impedance calculations
(OP)
I was wondering if anyone can give me a formula or somewhere I can find it to get positive and zero sequence line impedances and angles for a transmission line. Thanks
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Line impedance calculations
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RE: Line impedance calculations
cheers !
RE: Line impedance calculations
RE: Line impedance calculations
RE: Line impedance calculations
1- Is the transmission line underground or overhead?
2- What is the phase conductor size and physical configuration?
3- Any shield wire(s) and size.
4- Any information on soil resistivity?
RE: Line impedance calculations
2- 795 mcm ACSR and vertical configuration with all 3 phases on one side of a pole. It is a 46 kV circuit with a second circuit on the other side of the pole.
3- static line on top of pole
4- no info on soil resistivity
RE: Line impedance calculations
You will have to dig into either a power engineering handbook, or a wire company's electrical data (such as southwire) to get the positive, and zero sequence for a given length (usually per thousand feet). Find out how many feet of line you have and you should be able to calculate it out.
For your phase distance elements you can find the angle by converting from rectangular to polar form after you have the total line impedance. For your ground elements, the same applies, but I believe the 311A also uses a Ko factor which you will need to find the calculation for.
RE: Line impedance calculations
If injection is not possible find what type of conductors are used and refer to manufacturer information. For overhead lines the angle is around 75 Deg. If you can not find any information on conductors, use 0.4 ohm/km as a safe approximation.
RE: Line impedance calculations