Glowing conductors

[kwired]

With the hot weather and recent record power production and usage levels in the area, my wife has told me she had two different people mention on Facebook that they saw the power lines "glowing" after dark - likely from being overloaded.

I told her that I find that very hard to believe. I even find it hard to believe that high voltage transmission lines would not have overcurrent protection that would limit current to a level well below what is required before the conductor would glow.

I could see glowing connections happening where some resistance has developed - that connection is going to fail eventually but is not necessarily an overloaded condition, and the extreme heating would be limited to immediate vicinity of the failing connection.

Just wonder what others think - especially some of you that work with utilities

 

[Hv&Lv]

With the hot weather and recent record power production and usage levels in the area, my wife has told me she had two different people mention on Facebook that they saw the power lines "glowing" after dark - likely from being overloaded.

I told her that I find that very hard to believe. I even find it hard to believe that high voltage transmission lines would not have overcurrent protection that would limit current to a level well below what is required before the conductor would glow.

I could see glowing connections happening where some resistance has developed - that connection is going to fail eventually but is not necessarily an overloaded condition, and the extreme heating would be limited to immediate vicinity of the failing connection.

Just wonder what others think - especially some of you that work with utilities

We get calls of glowing conductors often. It is leaves brushing along the wires. We have some tree wire that is notorious for generating glowing wire calls because the right of way is so narrow.
If the conductor was glowing from load, the metals would be so soft they would pull apart under the line tension.

 

[K8MHZ]

With the hot weather and recent record power production and usage levels in the area, my wife has told me she had two different people mention on Facebook that they saw the power lines "glowing" after dark - likely from being overloaded.

I told her that I find that very hard to believe. I even find it hard to believe that high voltage transmission lines would not have overcurrent protection that would limit current to a level well below what is required before the conductor would glow.

I could see glowing connections happening where some resistance has developed - that connection is going to fail eventually but is not necessarily an overloaded condition, and the extreme heating would be limited to immediate vicinity of the failing connection.

Just wonder what others think - especially some of you that work with utilities

I dunno.....

Metals have to reach a high temp to exhibit incandescence. At that temp, the metal will sag and stretch and not be able to return to it's original length. If the temp gets high enough, a condition called 'incipient melt' occurs and the metal becomes porous, brittle and weak.

At night, it's going to take around 600 degrees to glow. Bear in mind that ACSR has one steel strand and the rest aluminum. Getting to the point of incandescent would put an enormous stress on the conductor.

Sounds fishy to me.

 

[kwired]

We get calls of glowing conductors often. It is leaves brushing along the wires. We have some tree wire that is notorious for generating glowing wire calls because the right of way is so narrow.
If the conductor was glowing from load, the metals would be so soft they would pull apart under the line tension.

The cases you mention with the "tree wire" (which I think I know what this tree wire is) is likely 600 volt and less I would assume. I am about 99% certain the cases mentioned that my wife was reading about was probably 12.47/7.2 kV lines.

 

[kwired]

I dunno.....

Metals have to reach a high temp to exhibit incandescence. At that temp, the metal will sag and stretch and not be able to return to it's original length. If the temp gets high enough, a condition called 'incipient melt' occurs and the metal becomes porous, brittle and weak.

At night, it's going to take around 600 degrees to glow. Bear in mind that ACSR has one steel strand and the rest aluminum. Getting to the point of incandescent would put an enormous stress on the conductor.

Sounds fishy to me.

Was kind of my thoughts. First I don't think they will carry enough current to reach high enough temp to glow without operating an overcurrent device someplace, but if they did carry that much current they are going to sag and will never recover from that, plus by the time it is dark enough to see such a thing the load has probably lessened some.

I have seen glowing on bad connections on med voltage lines, but this happens at any time of year but the heat and increased load may be helping to make connections fail.

I still think whatever these people have seen is a failing connection.

 

[steve066]

could it just be light (maybe from street lights) reflecting off the wires? Or even the moon reflecting off the wires?

 

[don_resqcapt19]

The old single conductors used for the secondary side of the transformers around here had a covering on them. I did see that "glowing" one night as a result of a short circuit that was not pulling enough current to open the transformer primary. It was actually burning and falling off the conductors. I have no idea how hot the conductor had to be to make that happen. It did look really cool.

 

[Hv&Lv]

The cases you mention with the "tree wire" (which I think I know what this tree wire is) is likely 600 volt and less I would assume. I am about 99% certain the cases mentioned that my wife was reading about was probably 12.47/7.2 kV lines.

No. you assume wrong. The tree wire I am speaking of is carrying 14,000 volts.
I doubt I could get a glow from leaves from 600 volts or less.

 

[SG-1]

No. you assume wrong. The tree wire I am speaking of is carrying 14,000 volts.
I doubt I could get a glow from leaves from 600 volts or less.

You mean the insulation was degrading & was producing corona ?

 

[broadgage]

As others post, it is most unlikely that any standard type of conductor could get hot enough to glow without either failing mechanicly or tripping OCPDs.

However, I did read some years ago about a proposed new type of overhead line conductor that could withstand very high temperatures, even up to the point of incandescence.
The idea was to increase the load capacity of existing routes, but was widely condemmed as an energy waste due to the much greater losses resulting.
POSSIBLY an instalation of this ?

More likely IMHO to be either an optical illusion, reflected light, or perhaps corona discharge if very high voltage lines.

 

[kwired]

could it just be light (maybe from street lights) reflecting off the wires? Or even the moon reflecting off the wires?

That also was something that I considered as a possibility. I really don't know what was seen or where it happened, was just told there were a couple people that posted on Facebook that the power lines were glowing from being so overloaded, my first thought was there is no way they can sustain operation at the temperature required to glow and they must be either looking at a point that is malfunctioning (and probably will not be for much longer), or was seeing something else and made an assumption.