You can think of three phase faults as an extreme case of high loading. Most of the time you don't have a perfectly balanced system and there will be neutral current. So if you have it during normal conditions why not during faults. The only difference is the impedances.
I had a customer request a 3phase 4 wire 120v l-n, 240v l-l wye connected voltage transformer. 120 l-n on each phase and 240 l-l across each phase. I had never heard of this? Does any utility use these? We currently have the 120/208 with three 120 l-n's and the 208 l-l. We also have the...
I have seen them used on a rural circuit with a small (600 kVAR) bank. We used a Nova recloser and operated on voltage. This was due to a large quarry type of customer causing large voltage flucuations on the primary. We would close instananeously during voltage dips.
I am another one that votes for switching hands. I did it when a while ago because my primary hand was causing me pain. I didn't like that so I quit doing what was causing me pain. Switching to the left side also had the added benefit of being able to type with the right at the same time, as...
I have talked with these guys. http://www.natiscomm.com/
They have made us some load loggers for the underground. They are very flexible with their product, just tell them what you want. We were able to get a encrypted wireless datalogger. We have used the sensorlinks for the overhead and they...
<<Delay the SEF tripping so more faults will be cleared by the fuses. Unless it lands on somebody, downed conductor is not a safety hazard untill someone approaches it.>>
I disagree. A conductor laying on the ground can cause fires. And if this results in a large forest fire it can result in a...
1. Settings adopted for such relays.
Where we have used them we set them to 10% of the Grd trip setting.
2. Whether they face similar SEF relays operation caused by reasons other than fallen line conductors. If yes, what procedure do they follow to restore the supply? Do they patrol the whole...
I'm sorry I can't comment on the arching horns. But I would persue the relay reports to see if you are getting a fault in the same area each time. This would pinpoint a problem area rather than just suspect the whole line.
After reading your problem, it brought to mind a problem I had with...
50-60% unknown cause is awful high. We occasionally have a weak link that just falls open or one that clears and doesn't fall down, but that is not the norm. We use a lot of fuses on our overhead tap lines and transformers. After a fuse operates we generally find a cause by patrolling the...
I'll assume you mean low voltages only.
we have the following transformer secondary voltage levels.
120/240 VAC
120/208 VAC
240/480 VAC
277/480 VAC
Jasjit Khangura P.E.
Electric Distribution Engineer
Most automobiles use 12V for everything. I would think that anything significantly over that (25v+) would cause most things to fail. Not sure about the coil itself thought. However for a newer car, it will not run without a functional computer.
Jasjit Khangura P.E.
Electric Distribution Engineer
Hello All,
I am looking for more information regarding the characteristics of and protection of autobanks. I have a 21 kV 4 Wire feeder feeding an autobank as well as other connected load. The autobank is a 21/12 auto Y connected with H0/X0 grounded and closed tertiary. The 12 kV side is also...
How would the protection requirements change at the power tranformer, especially under light loading situations?
Jasjit Khangura P.E.
Electric Distribution Engineer
SF6 gas itself will not need replacement because it doesn’t get used up, but every time there is an arc a toxic/corrosive residue is left which after a while will build up.
However water and air molecules in the gas can combine with the contamination and eventually lead to a dielectric...
