Blown Transformer Cutout

mbrooke

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Steel and concrete building structures are very good protection from direct strikes. This sort of gives you a cage around the contents as well as anything nearby but below it enough that it is protected by the “lightning rod”.

Then it’s just a matter of avoiding indirect strikes...surges traveling down the conductors outside the building.
yup- thats what I've theorized. NY high rise buildings are the safest overall.
 

mbrooke

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Not the good ones...
Read the wire, not the maps
Thats kind of hard- 4kvY segment re-built but not upgraded voltage wise. In-line strain insulator- step down bank is off on a side road. Easy for a stressed out crew to think they are still on 12kv when all looks identical.
 

Hv&Lv

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Thats kind of hard- 4kvY segment re-built but not upgraded voltage wise. In-line strain insulator- step down bank is off on a side road. Easy for a stressed out crew to think they are still on 12kv when all looks identical.
For the good linemen, it doesn’t look identical.
You have to look at it all and know where you are at.

just saying...
 

mbrooke

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Another scenario. Dual-feed circuit. We are in alley behind Joe's. Is the open point here or there? We think it is circuit 123 but it might be 124. Buzz line and call for open on circuit 123. Line no longer buzzes. We dropped the correct circuit and it is good for safety grounding.

Still gets grounded for work. No buzz doesn't mean there isn't a lower voltage or static present so only an idiot would grab it unless protected.

Buzzing is a useful tool. But not the only tool for all situations.

Forgot to ask- does an MOV activating (shunting) trigger a trip and reclose?
 

Hv&Lv

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4kvY rebuilt to 12kvY waiting for that final flip on the back of a few pigs looks identical.
12.5kV being switched to 25kV does also. We do it all the time.

Again...
if you don’t know where you‘re at, stay away from it.
 

mbrooke

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12.5kV being switched to 25kV does also. We do it all the time.

Again...
if you don’t know where you‘re at, stay away from it.
I know but its easy to get it mixed up. Picture neighborhoods that alternate feeders for miles.
 
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Hv&Lv

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I know but its easy to get it mixed up. Picture neighborhoods that alternate feeders for miles.
I do this everyday, and have for over 30 years...
Just because you don’t understand it doesn’t mean experienced linemen don’t understand it also...

tell me again.. you have how much experience with it??
 

Hv&Lv

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Is there any way that can be avoided?
With trip settings at 340A on a 105, 3500A available fault current, and the MOV shunting to ground its going to happen.

I will say I’ve noticed some places place current limiting fuses ahead of the MOV, with little success from what I have heard.
 

mbrooke

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With trip settings at 340A on a 105, 3500A available fault current, and the MOV shunting to ground its going to happen.

I will say I’ve noticed some places place current limiting fuses ahead of the MOV, with little success from what I have heard.
105 is your cooper recloser curve?

What I never understood is that individual pole pig cutouts don't seem to blow, but lateral 65K fuses do... unless they've got fuse blowing and as such tree limbs, not lightning, is doing it.

Does Spacer cable help?
 

mbrooke

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I do this everyday, and have for over 30 years...
Just because you don’t understand it doesn’t mean experienced linemen don’t understand it also...

tell me again.. you have how much experience with it??
I do not doubt that you've been doing this for 30 years. I'm sure you can figure anything out.

However, I can't see someone not making an error in the heat of the moment. Years back there was actually a line guy who hooked up a 240/480 volt pig in place of a 120/240 in CT when on an emergency call pressed for time.
 

Hv&Lv

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105 is your cooper recloser curve?

What I never understood is that individual pole pig cutouts don't seem to blow, but lateral 65K fuses do... unless they've got fuse blowing and as such tree limbs, not lightning, is doing it.

Does Spacer cable help?
Tree wire is bad enough to repair during a storm.
the tree wire helps tremendously on blown fuses..
unfortunately it’s very unsafe IMO.
I have witnessed it arcing to earth laying on the ground and not blow the fuse.
It does make VERY SHARP “glass”
(ask how I know how sharp it is...)
I definitely wouldn’t consider spacer cable in a rural setting. The cost of restoration would be ridiculous.
 

mbrooke

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Tree wire is bad enough to repair during a storm.
I definitely wouldn’t consider spacer cable in a rural setting. The cost of restoration would be ridiculous.
Tree wire alone is worth the service continuity. Spacer cable is beyond wires a God send.

But- does it help with lightning? Can it reduce or eliminate recloser blinks during nearby strikes? Or even direct hits to the messenger?

Understanding/modeling lightning has never been my strong point.
 

mbrooke

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Tree wire is bad enough to repair during a storm.
the tree wire helps tremendously on blown fuses..
unfortunately it’s very unsafe IMO.
I have witnessed it arcing to earth laying on the ground and not blow the fuse.
It does make VERY SHARP “glass”
I definitely wouldn’t consider spacer cable in a rural setting. The cost of restoration would be ridiculous.

Unsafe? Then ratchet it to a messenger! :D
 

mbrooke

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you should try to put that back in the air when ice or trees lays it down.

It doesn't stop National Grid from using it, or a half dozen Municipal utilities in Massachusetts. I've heard of sheer brackets...

I know linemen abhor it and say it doesn't do anything- to them I'll just say grow a pair... especially how many of you are supposedly X military. Suck it up butter cup.

Yes I like Spacer Cable :D

But anyway, how does it do during lightening?

It would be nice to have fuse blowing enabled during a thunderstorm in a fused spacer cable tap off a spacer cable trunk line.
 
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