Transmission Line Drop

[tonyflair]

The following transmission line is being considered:
ACSRSL 167.7 6/1 Pigeon 3/0 25C

If the above 3 phase line was stretched a distance of ~8000 ft, would it be expected to see a large drop over the line ?
i.e. should the current at the end of the line differ a lot (if any) from the current at the start of the line (given this type of line and length) ?

The reason why I ask, is that in simulations the current doesn't really differ at all.....just curious to know if that is normally or if a parameter is modelled incorrectly.

Thanks in advance

 

[jghrist]

The current going into the beginning of the line has to come out the end, except for the part that goes through capacitance to ground and other phases, and that's negligible for a 8000' line.

Normally, when you talk about drop over the transmission line, you are talking about voltage drop, which depends on the amount of current and the impedance of the conductor.

 

[CJFlatters]

Look at the 'nominal Pi' method for modelling of transmission lines, it is relatively accurate representation.

Even if the receiving end is open circuit, you will still get capacitive charging current flowing in the line as mentioned by jgchrist.

_______________________________________
Regards -

Colin J Flatters
Consulting Engineer & Project Manager