If it's rated at 100KVA, that's only 400A, 150% is 600A. You would get higher than that for whatever period it takes to blow the primary fuse. So what happens if there is a direct short? The wire melts before the primary fuse can blow?
Typical service rated
That's only 200A, 150% is 300A, but the primary fuse won't do anything for a direct short because the wire will melt first?
There was a field full of them up at the power station at
Here they will put one house on a 25KVA, 2 will be on a 37 and 3 will be on a 50. There are a couple of 50s here with 4 houses on them but I bet that will change if they tear down those little 1300 sq/ft PreFIRM shacks and put a 2000 Sq/Ft house there. A lot of this infrastructure is 60 years old and predates wide spread use of A/C and other heavy hitters.
This is the map of my primary. I am about 1/3d of the way down from the tap off the distribution trunk.
There is usually a number on the transformer that tells you the size in KVA (25/37/50 are common here)
That disconnect may be part of a breaker. I saw where one tripped and the lineman pushed it in with a long pole. There may be 2 sperate devices for all I know of it.
I'm sure there is (or at least was) but I can't read anything from the ground...
On 7/13/2020 4:13 PM, snipped-for-privacy@aol.com wrote: ...
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Ice and wind caused lines to touch a couple winters ago -- recloser tried however many times and gave up.
I made the presumption didn't need call CMS 'cuz neighbors also were out (of course) and the one to the south of us is on board so he always reports.
What I didn't know at the time is that we are the only one one the third phase and it reopened after they reset manually. I didn't realize until dark that everybody else did have power; we were the only ones that didn't.
By that time it was another two days before they could dispatch a crew back this way the 50 miles for one lone farmstead given the widespread ice damage they had farther east.
That is the disconnect.
I have a note in to the guy who knows but he hasn't gotten back to me. The fuse might be that long tube below the disconnect.
Look at that stuff above the transformer, connecting it to the primary on the top of the pole.
These days, with the smart meters, we don't even need to call. The system knows which meters have stopped calling home.
They've gotten them in since then, but I'm not sure how far they've gotten w/ the software system. Annual meeting is coming up soon; I'll have to try to ask if Kirk doesn't say where that is in his status summary...
The disconnect can either be just a disconnect or it can contain a fuse that when blown will let the disconnect fall down so it can be seen from the ground. I thought I remember seeing one of those that had fallen down when a fuse blew, but it had been around 15 years ago.
Yup that is what my FPL buddy told me this evening.
That's a good find. I've seen the disconnects on poles, never knew about how the fuses worked, that they drop down to indicate they are blown.
On Mon, 13 Jul 2020 15:12:15 -0500, dpb posted for all of us to digest...
Ted Kaczynski? 8-)
On Mon, 13 Jul 2020 20:17:00 -0400, snipped-for-privacy@aol.com posted for all of us to digest...
The fuse is the white stick next to the insulator equal-distant between your 13.5kv and neutral notations. Second insulator from the top of the pole with a standoff from the pole.
On Mon, 13 Jul 2020 20:18:59 -0400, snipped-for-privacy@aol.com posted for all of us to digest...
And ringing the cash register :-(
On Tue, 14 Jul 2020 00:01:16 -0700 (PDT), trader_4 posted for all of us to digest...
Not necessarily, they can weld themselves into the holder if the clamps at the top loosen. They can become so hard to remove the PoCo has to shut the primary down to fix it. Around here where we have many trees in wires and the utility was less than diligent in pruning as a firefighter I witnessed a few spectacular shows.
I watched a lineman pull one of those cutouts on a humid and very overcast (so fairly dim light) day.
He pulled fast, with a hard yank. The arc that followed the cutout down and away was almost 2 feet long and looked like a miniature lightning bolt. It was not bright, I wouldn't have seen it on a sunny day.
This is similar to what runs down my alley and is common throughout the city.
My secondary rack - "120/240" - has the neutral as the center wire. Looks like your neutral is on top (where service drop support connects).
One phase of the 3-phase distribution runs down my alley and is 8kV phase to neutral/earth (about 13.5kV phase-to-phase).
My secondary neutral is bonded to the transformer-can. The can is the primary neutral. My primary neutral is the same as the secondary neutral running in the secondary rack.
Any pole with a transformer (and some others) have the neutral connected to an earthing electrode. Some are ground rods. I think some are disks on the bottom of the pole. Neither is likely very effective, but there are may of them in the system.
Most transformers here have a fuse, like in your picture. The transformer I am on is connected directly to the primary and has an internal overload. It is reset using a "hot stick" on a lever on the side of the transformer.
The wire from the cutout drops to an insulator attached to the transformer can. I presume this is a lightning arrester that directly limits the voltage across the primary.
The wire from the cutout attaches to the primary feed with a clamp that has a ring on the end of a screw, barely visible. A lineman can attach a hot stick to the ring, unscrew the clamp, and safely disconnect the cutout and transformer.
I have seen some of them that were blown. When you know what it is it is pretty obvious.
Yeah, but what's the fun in that... :)
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Thanks...was just wondering about whether might be one of those staples to have on the shelf or if would always be (like the PVC cement) dried up when did need it so have to go to town, anyway.
That's kinda' the answer figured 3M would tell me... :)
Yeabut - wheres the video????
Had one blow about a block away from a quite solid short. It was a loud bang inside with windows closed.
An 8kV wire broke midspan. The source end fell against a box for cable distribution and put a nice burn mark on the corner. Someone moved the wire out of the street. He was real lucky the wire faulted, else he would probably be dead instead of the feed. The other part of the wire came down in an alley. It was part of a 3-phase tap. Question was whether it was live or dead. When the lineman moved it (with insulated gloves) it arced through several times to the concrete. It fed a
3-phase transformer for a building - that apparently back-fed it. I think these wires are "covered", not "insulated".HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.