Inner conductor damaged...why?

[230kv]

Four days ago we get a big and strange problem, that 380 kv line 4 bundle conductor one phase broken from the middle span on the spacer damper clamp. We analyses this damaged that the damaged start from inner strand going to outer strand due to high vibration.
What is your opinion for this case?
Did there is any instrument can discover inner conductor damaged –unseen-early?

thanks

[Alan Mac]

The only thing I can suggest is a device known as a corrosion monitor - Cormon. We use it on our lines, it gives a reading of the level of loss of galvanisation on the steel core. It's non destructive, just a remote control buggy and a sensor head that you run out on the conductor.

http://www.cormon.com/services/ohlcd.aspx

They are UK based but travel all over Europe, no reason why they couldn't come to you. Do me a favour if you do get in touch, mention that they were recommended by SSE.

Of course, if the damage was caused by vibration, this may not help, but let us know how you get on.

Mac

[230kv]

Thanks Alan Mac
I forget to mention that this conductor not ACSR it's ACAR also the spacer damper clamp was tightening very will....we didn't find any looses.

[johnbellamy]

We shoot are lines with an ifrared gun to find weak connections, or weak spots spots in the line you cant see with the eye. I don't know if this will work well on that high of voltage though, just a thought,

[barehander]

We shoot are lines with an ifrared gun to find weak connections, or weak spots spots in the line you cant see with the eye. I don't know if this will work well on that high of voltage though, just a thought,
It will work, and there should be a hot spot where the wire is bad under a spacer.

[Edge]

It will work, and there should be a hot spot where the wire is bad under a spacer.

Yeah I gotta agree with 'hander and 'bellamy this should work... ACAR... sounds like vibrations or may be strain when pulling in or sagin' have seen that before usually at deadends though when the wrong type of grips where used....

for what its worth bud...

Edge

2 steps aint' enuff

[Squizzy]

I used to do a fair bit of Thermographics , going through all substations and terminal substations with a thermal imaging camera. If there are any hot spots on the line it will will show up real good if you have it set right. A difference of a couple of degrees will be clearly visible and if it shows up this particular problem its also very quick to do.

[BigClive]

There are also corona discharge camera's, but I'm not sure how they work. I did see some video footage on YouTube of one in action, but couldn't find it again. I get the feeling they detect some particular wavelength of light from the corona. Maybe they just detect the minute light level emitted. The image certainly seemed to show a flurry of activity when the camera was moved, suggesting it is just a very sensitive optical threshold.

The corona would indicate a frayed or damaged conductor.

[BULLogna]

was the wire near any type of chemical plant or refinery. cause weve had a lot of conductors near refinerys that have the steel core ate out. acsr and copperweld. Ive also seen lighting remove the core of a 110 shield wire. we contract testing it is infared but all i get to see is a picture showing the hot spot.

[230kv]

Thanks every body
Unfortunate we used infared camera we didn't fined any hot spot:confused: …actually maybe because the outer conductor still not yet damaged... That's why we need like X-ray camera to inspect inner conductor condition...when we find any damaged we can repair before going to outer conductor ..

There is no any type of chemical plant or refinery near this line

[BigClive]

Was the break right where the clamp was? If so it could have been the movement of the cable. Perhaps there's some environmental or structural contributor that causes excessive movement of the cable.

Other than that it might possibly just be a manufacturing fault. Did you keep and examine the area that failed?