I’d like to get your thoughts on the best grounding practices for overhead line structures equipped with surge arresters. My understanding is that surge arresters should have the shortest possible path to ground via a dedicated ground wire. Additionally, other pole-mounted equipment (power...
Can someone point me to the industry references for the typical outage rates for overhead powerlines? I am performing the reliability assessment study for our distribution lines and would like to have a reference to benchmark against.
Is there any merit to conduct HI-POT on the autoreclosers during periodic maintenance? Some vendors maintenance manuals recommends it and some leave it for users to decide. Our challenge is most of our reclosers are mounted on the poles so conducting Hi-POT on these reclosers is bit of...
Thanks for the suggestions everyone. I guess what I was trying to ask if there is a merit to do the periodic ground resistance measurements for the structures like every 5 years or so. Visual inspection would able to identify any missing ground links due to theft etc. However, things like change...
Most of our steel poles have concrete footings. We have some old wood poles in our systems, which are directly buried. The measured footing resistance was above 100 ohm on affected structures.
We are not a utility, but we manage a large network of distribution and transmission lines that feed critical loads. Recently, we experienced some lightning-related outages on our 34.5kV circuits. Upon investigation, we found that the footing resistance of the structures was quite high, leading...
I recently got in debate with a coworker on the right way to connect the surge arrester across the terminal of the equipment it is suppose to protect. I have attached a sketch for both options which came under discussion. To me both options are electrically same with option 1 offers a shorter...
Anyone here with the experience of using arcing horns on distribution voltage (35kV) overhead Powerline insulators? We have one old line which has ceramic insulators with the creepage distance not suitable for the area, so we are evaluating the option to replace the insulators with the polymer...
Hello all..... we have 13.8kV distribution line which runs near the costal area and we recently experienced few flasover where the inusulator show arc marks on the top shed and the bottom shed only. Installed insulators are composite type with silicon rubber shed and 40mm/kV creepage distance...
I have seen guys doing the conductivity test by shorting the three phases together from one end and then using insulation tester MEGGER to apply 5kV DC between two phases and observe the reading.
Hello Everyone.. what are the typical re-commissioning electrical tests for overhead powerlines? I understand for long distance HV (230kV and higher) you would normally perform phase sequence/rotation check, sequence impedance tests, conductivity tests and footing resistance tests. My question...
Hi All..... We have two old 115kV line running parallel to each other with insufficient clearance between each other. During windy season, we get outages on these lines as conductors of one line come in contact with the structures of the other line. We are evaluating options to fix this issue...
Hello all...... We have a situation where we need to load ACSR conductor in 120-130 deg C range. I am trying to figure out how long (hours, weeks, months?) a conductor can be operated above the normal operating temperature before aluminum starts to anneal and conductor strength gets impacted. If...
Thank you everyone for the suggestions. We are currently evaluating this product by EPRI https://www.epri.com/research/products/1020243, which seems to be specifically designed to measure the grounding performance of the electrode by simulating the lightning surge.
Substation structures (buses , jumpers) don't see longitudinal loads similar to what a typical full tension span see, so the governing loads are usually short circuit forces for these structures including the gantry structures which are most of the time are slack spanned. Typical powerlines ...
Anyone here has experience with measuring ground resistance of tower/ structure footing? What testing tools are typically used by utilities to determine the footing resistance? We recently had few back flashovers on our power lines, so we are doing the root cause analysis and starting with the...
Would you be involved in the actual research or mainly managing the research as a project manager? if you are involved in research & development then you shouldn't have any problem getting back into the engineering side of things. If you are mainly managing the research projects as a project...
Did you try getting in touch with Hubbell Power? Chance was acquired by them, I have used used these power helix anchors on multiple jobs here in Alberta.
Shield wires are considered better protection against direct lightning strikes. Surge arresters provide better protection against induced voltages.
Creep is due to structural/mechanical properties of the conductor, I don't think you can prevent. We normally take creep into account when doing...
