Where are the lightning arrestors?

[mbrooke]

Why cant I find them :blink:

 

[ron]

Those are air terminals which are part of lightning protection, and surge arrestors which inadvertently are part of a lightning protection system. Both found in NFPA 780, but 780 doesn't apply to utility structures.

 

[fmtjfw]

none are in the picture. There are no static lines above the station nor any lightning rods.

 

[Smart $]

Why cant I find them :blink:

Not sure, but aren't they mounted atop the short square tower frames (one in foreground, other off to right)...???

 

[gar]

141222-1327 EST

My guess is the same as Smart $. That small object bridged across a line pair would have no other purpose. There doesn't appear to be any other connection than the two high voltage posts.

.

 

[mbrooke]

141222-1327 EST

My guess is the same as Smart $. That small object bridged across a line pair would have no other purpose. There doesn't appear to be any other connection than the two high voltage posts.

.

But why only bridge 2 phases, why not all 3?

 

[mbrooke]

Those are air terminals which are part of lightning protection, and surge arrestors which inadvertently are part of a lightning protection system. Both found in NFPA 780, but 780 doesn't apply to utility structures.

Where are the air terminals? If the pointed things those are arcing horns designed to pull an arc upward in an effort to extinguish it.

 

[fmtjfw]

Not sure, but aren't they mounted atop the short square tower frames (one in foreground, other off to right)...???

Potential transformers? Two primary bushings, secondary conduit.

 

[fmtjfw]

The things sticking up are arc horns for the air switches, not lightning rods (air terminals).

 

[iwire]

Here is a labeled picture I found on the web, it might help.

 

[Frank DuVal]

Good picture. Around here, the 34.5 kV side would be the distribution lines! Here, only old substations still do such low voltage distribution in inner cities.

 

[Smart $]

Potential transformers? Two primary bushings, secondary conduit.

IDK... the OP asks about lightning arrestors, but the picture caption says "Surge (lightning) arrestors...". My impression is they are not the same. Air terminals typically extend to the highest point of the yard. Some yards use several parallel wires from side to side.

I've worked plenty of power plants, but never in the switch yard or at a substation. Closest I got was replacing a plant to yard step-up transformer.

Anyway, here's a link to a fairly comprehensive guide for substation design:

http://www.rurdev.usda.gov/supportdocuments/uep_bulletin_1724e-300.pdf

There's a good picture of air terminals on the front. If anyone wonders why it's published by the USDA, it's for heavy farming community co-ops.

 

[mbrooke]

Potential transformers? Two primary bushings, secondary conduit.

We have a WINNER!!!!!!!!!!!!!!!!

Yup, those are potentials, most likely for the motorized air break scheme. (This is probably a sectionalizing substation, so when a circuit trips the air breaks open and which ever feeder successfully recloses the air breaks re close to bring the substation back on line)

The truth is I don't see any lightning arrestors in that pic, so I guess the author thought those voltage potential transformers were the lighting arrestors.


BTW, this is from the McGraw Hill NEC handbook

 

[mbrooke]

Here is a labeled picture I found on the web, it might help.

15kv feeder Oil breakers aren't metal clad switch gear, and those lighting arrestors are part of what look like manual air breaks.

Pics like that are not to be trusted.

 

[mbrooke]

Good picture. Around here, the 34.5 kV side would be the distribution lines! Here, only old substations still do such low voltage distribution in inner cities.

Who knows of those are 34.5, I wouldn't trust anything on the net.


However, you are correct. 34.5kv can be either sub transmission or distribution depending on system age and POCO design standards.


Generally, the theme is to add an MGN and bypass the intermediate substation when dealing with voltages of 35kv and below. A recloser loop scheme is often added to simulate the reliability that 2 redundant sources to intermediate substations gave.