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hey Zog, what is this?

4K views 42 replies 19 participants last post by  CheapCharlie 
#1 ·

















It says dry air filled, like dry ice?? What about those cylinders like fpr torches, some sorta accumulator?
 
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#2 ·
It's an oil-filled something that's missing the bushings and the oil and radiators. Those three metal cylinders get opened up and that's where the three huge-ass HV bushings bolt in. And those white caps on the sides are where the cooling radiators attach.

They ship it filled with dried air because even normal atmospheric air has enough moisture to contaminate the coils. Then when it's on site they fill it with oil to insulate it for service.

Most likely a transformer, but there are a lot of big grey boxes that look like that.

-John
 
#9 ·
Big John nailed it, that support bracket in the last photo is for the conservator tank.

Usually shipped full of nitrogen, when we fill that bad boy you have to keep it at a vacuum the whole time, the oil is heated, filtered, and degassed during the filling process. Do it all the time, that one isn't very big though.
 
#10 ·
Zog said:
Big John nailed it, that support bracket in the last photo is for the conservator tank.

Usually shipped full of nitrogen, when we fill that bad boy you have to keep it at a vacuum the whole time, the oil is heated, filtered, and degassed during the filling process. Do it all the time, that one isn't very big though.
Now that you mention it, Zog, can't tell how really how large from the photo. The unit I mentioned was a large tertiary (?) unit that was designed for OGE. Can't rightly remember who built it, though.
 
#19 ·
Anyways, to answer the question, they use those flatbed trailers with a bazillion wheels, some are so big they have to close roads ahead of time and get police escorts.
 
#26 ·
I worked at the Ohio Transformer plant in Palmetto, FL. They used to hand wind the coils and they were so large the workers stood in the center, maybe a dozen Cubans in the middle of a huge coil winding it for weeks.
 
#27 ·
BTW, those boxes on the lower left in the first pic are where the terminals are for the protection relays and current transformers.

A transformer this size is not just energized then left alone. It has a bunch of relays installed on (and in) it. They monitor stuff like oil temp, winding temp, tank pressure, oil level, etc.

These relays go to some sort of a panel that has other relays in it. They decide if a condition requires the feeder breaker to trip or is just an alarm.

My favorite relay though is the silver one on top between the left and center bushing wells.

This is the 'Sudden Pressure Increase' relay.

Any guesses as to what would cause this one to trip?
 
#30 ·
FulThrotl said:
yeah, it's called bowsering, or polishing the oil.

pull a very good vacuum, and circulate the oil for a couple days at least, letting the water vaporize out, do leakdown checks every hour, and sample the oil....
and heat it up to 150 or so degrees F.....
How hot does it run at?
 
#39 ·
depends on the oil, what the maximum safe temperature is,
before the oil begins degrading....

and depends on how desperate supervision is to get the oil
dry enough to pass test.... 175 degrees F seems to stick in
my mind, but it was 8 years ago last time i did one.

they were trying to put an old GE back into service after one
on the same site blew.. they moved it a few hundred yards
down the line, and connected it up... and it hadn't been
mothballed well, and the windings were damp, and nothing
that was tried really dried them out.
 
#32 ·
How common are Buchholz relays on these things?

A couple of our trannys have them in addition to a sudden-pressure, and in one case as a replacement for a SP, but it always seems to throw the testing outfits for a loop where their techs never know what it is.

Not sure if these just aren't used widely anymore or else the techs are incompetent.... :whistling2:

-John
 
#34 ·
How common are Buchholz relays on these things?

A couple of our trannys have them in addition to a sudden-pressure, and in one case as a replacement for a SP, but it always seems to throw the testing outfits for a loop where their techs never know what it is.

Not sure if these just aren't used widely anymore or else the techs are incompetent.... :whistling2:

-John
Fairly common, testing is pretty simple, just simulate the oil inrush using dry air, and vent when you are done, there are built in valves for this.
 
#33 ·
All the transformers we have come with sudden pressure relays. When we have a transformer delivered it doesn't even get unstrapped until we do a core ground test to make shure nothing shifted during the haul. Then once installed we do our normal commissioning powerfacter,ttr, and megger test.our relay department does all of the relaying and protection devices
 
#38 ·
micromind said:
A transformer this size is not just energized then left alone. It has a bunch of relays installed on (and in) it. They monitor stuff like oil temp, winding temp, tank pressure, oil level, etc.
?
What are average oil and winding temps? Do temps vary based on transformer size?
 
#41 ·
What are average oil and winding temps? Do temps vary based on transformer size?
The design average oil temp is 25 degrees C above ambient, hence the 25C reference point of the level gauge, that is where the oil level should be at 25C. The size is not so much a factor because the designs are all the same, obviously loading and ambient tempature are the 2 biggest factors.

Another factor is cooling system type, of which there are many possible designs, OA/FA is the most common on smaller liquid filled.
 
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