OK Power company guys ....... What is it?

Status
Not open for further replies.

iwire

Moderator
Staff member
Location
Massachusetts
NHPOCOUnit13.jpg

I saw this near where I am vacationing.

Is it a voltage regulator?
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Do a patch around the blown up one, while the parts are being sourced to repair it.
 

PetrosA

Senior Member
We've got a lot of them sitting in our area, mostly near newer developments. I figured the POCO miscalculated their AC loads and had to boost things a bit ;) IIRC, they're mostly stepping down from 12kv to the 4kv lines here.
 

72.5kv

Senior Member
A mobile transformer. Looking at set up it looks its an autotransformer. The incoming feed maybe 24kv and out going 13.8Kv. Its about 5-7MVA. This is a common practice
 

bob

Senior Member
Location
Alabama
That is a mobile substation. Utilities will use this sub when there is a need to take an existing sub out of service. The utility may be taking the old sub out and replacing it with a new one. The length of time it take to do this requires some method to keep the power flowing.
 

cadpoint

Senior Member
Location
Durham, NC
Besides the trannie sitting there, can't one tell the approximate power in and out by the isolation fin's at each end, as shown?

I'm not sure of exact name of disc's...

I thought it was 2KV per isolation disc...
 

zog

Senior Member
Location
Charlotte, NC
A mobile transformer. Looking at set up it looks its an autotransformer. The incoming feed maybe 24kv and out going 13.8Kv. Its about 5-7MVA. This is a common practice

That seems about right but it looks more like 20-30 MVA and 35-70 kV. Hard to tell without someone in the picture, where were you Bob?
 
Last edited:

zog

Senior Member
Location
Charlotte, NC
Besides the trannie sitting there, can't one tell the approximate power in and out by the isolation fin's at each end, as shown?

I'm not sure of exact name of disc's...

I thought it was 2KV per isolation disc...

No such rule. well not really. Every area of the country has different kV/disc standards, depending on environmential conditions and the ratio has changed many times over the years in each area depending on vintage of insulators used.

I read a great white paper on the different ratios, very interesting (to me), I will see if I can find it again and post it.
 

72.5kv

Senior Member
most transformers over the 7MVA rating will have the radiators on it and the above that the cooling fans and oil pumps. At best those bushing are 35kV rated.

The largest transformer I have workout around is 1500MVA. Each phase is 500MVA 525kV in 241.5kV out.
 
Last edited:

iwire

Moderator
Staff member
Location
Massachusetts
I had to run out to dinner ......

Do a patch around the blown up one, while the parts are being sourced to repair it.

I do not understand.:confused:

Looks like an amusement park ride, your on vacation, hop on.

Have the wife take pictures.

Wait for me!!! I want to turn it on for Bob!

You guys are the best. :grin:

Funny it did remind me of a ride as it had a strong smell of hot oil.

Its an electric only tractor trailer. Crash testing hasn't gone well yet.

:grin:

most transformers over the 7MVA rating will have the radiators on it and the above that the cooling fans and oil pumps. At best those bushing are 35kV rated.

This appears to me to have pumps, fans and radiators.

Hear is a picture of the other side.

NHPOCOUnit05.jpg


Close up.

NHPOCOUnit10.jpg


The fence was really in the way of good pictures, I will have to go back with bolt cutters.




Here is a map, the unit was at the intersection of White Moutain Road and Village Road.

POCOUnitMap.jpg


There is a set of primaries running North South along White Mountain Road, there was another set connected to them running East along Village Road.

At some point you can see they cut the set heading East free from the North South set and put this unit into that circuit.

There are no other sub stations I have seen but they would be easy to hide in the hills and valleys.
 
Last edited:

dbuckley

Senior Member
This appears to me to have pumps, fans and radiators.

The additional cooling improves the short term rating of the transformer.

Utility transformers are designed to be overloaded to hell and back and still work for 50 years, and additional cooling allows a bigger or longer overload. Particularly handy when a substation drops out of service and another has to shoulder the additional load for a while.

All of the zone substation transformers installed in the last few decades have addition forced cooling hereabouts.
 
Status
Not open for further replies.
Top