Static wire holder arcing to ground ???
Static wire holder arcing to ground ???
(OP)
Recently we've trip on our 33 kV feeder due to static wire dropped or fell on to overhead line.
The problem was the holder/stud dedicated for static wire is broken.
The temporary result of investigation, the stud is eaten by arcing to pole rebar (it's a concrete pole). My temporary conclusion is the rebar on the pole is not a good ground,so its eaten by arc and in long time the tension of wire snap the stud that already thin. The pole position is in the curve of the line.
Is it possible the induction voltage on static wire do such a thing ? (the pole is beetwen two grounding point of static wire)
Please advice.
The problem was the holder/stud dedicated for static wire is broken.
The temporary result of investigation, the stud is eaten by arcing to pole rebar (it's a concrete pole). My temporary conclusion is the rebar on the pole is not a good ground,so its eaten by arc and in long time the tension of wire snap the stud that already thin. The pole position is in the curve of the line.
Is it possible the induction voltage on static wire do such a thing ? (the pole is beetwen two grounding point of static wire)
Please advice.
RE: Static wire holder arcing to ground ???
RE: Static wire holder arcing to ground ???
Tanks for your prompt response,
Yes it is lightning shield conductor on the top of the pole,(above the 33kV line) with fiber optic in it for transfer trip from end user XFMR to our breaker.
My question is,
Is it possible for this wire bleeding its induction voltage bleeding trough pole rebar before its bleeding trough dedicated ground ? (the pole that had this problem is in between two dedicated ground point).
What is the standard for grounding this conductor, the distance I mean ?
RE: Static wire holder arcing to ground ???
I had a similar problem on my 13.8kV system about 5 years ago. We had a pole top guy wire, guying a pole, burn off and detach from the pole. Upon investigation, I concluded that the guy had a much lower impedance than the vertical down ground, 20 ohms verses 450 ohms, respectfully. However this was not the root cause. With further investigation, it was observed that during inclement weather, the insulating deadend on C phase was indeed tracking to groung.( pole crossarm) We observed this first with a infared camera, then confirmed it with a HV test across the deadend. We changed the deadend, drove 2 ground rods, and installed a #2 cu vertical grd.
You might have something breaking down on that pole, which is searching for ground. You mentioned that it is inbetween two ground points. If something is breaking down it seems possible that it is using the static wire to get to the next low inpedance ground point. The clamps that hold the static wire to the pole are not usually designed with electrical conductivity in mind, thus a higher impedance. This is where resistive heat will be present and possible failure.
Chris
RE: Static wire holder arcing to ground ???
Yes we have to change 2 insulator on phase A (pole position is on curve of the line). We'll check the ground resistance on that two points.
On your post I conclude you end up installed #2 cu vertical ground in every pole ???
RE: Static wire holder arcing to ground ???
It sounds to me you found the root cause of your problem..now if you install a better ground on that pole next time it would hopefully trip the breaker quicker, causing less damage. Then you face the challenge of locating the cause of the feeder operation or lockout. Thats where the infrared camera really helps us out. It can pick up a differnce of 5 degrees F.
RE: Static wire holder arcing to ground ???
What is the standard of pole grounding resistance ? (anyone can help me)
tanks
yamin
RE: Static wire holder arcing to ground ???
1. Use larger diameter ground rods.
2. Use longer ground rods or ones that screw together.
3. Putting two, three or more ground rods in parallel.
4. Chemical treatment of the soil.
Check out the National Electrical Code or the American Electrician's Handbook for further details.
Chris