so umm... the fuse blew in that old black csp pot

[altecworker]

Anyway, last night we came in to a dark house, and i git my flash, and shine spotlight on the pole, no transformer... Soooo i'm thinking "what did a coon do, steal it?" then my mind gets right, and i think logically. Then i go up to the front door, note from DPCo. "We will be back shortly with a transformer, yours failed"

Anyway, so we wait, and sure enough about 20 minutes later i hear the sound of a dt466 being rodded to death coming down my street.

They tell me they dont have any new 2400 volt 50kva transformers, so they are going to put up another old one. Yep, you guessed it... not as old as the one i had, but made out of cast-iron with the multiple clamps around the tank lid, made by general electric i believe. They said "it's a known good pot, but just the same, we will come back in a few days and replace it with a brand new one" I told them, that if it a known good transformer, why replace it again, as i appreciate old power equipment.

Anyway, i know it sounds stupid as all hell, but i honestly dont want them to replace it....

Is there a way i can prevent them from replacing it? I know it sounds silly, but i have seen these old buggers, go for 70 years. and this one was manufactured in the 50s, or so i was told. Has been refilled with non pcb oil.

Anywho, i hate to post this kind of stuff here, but hey, there are no other linework forums, right? I also figured it was a odd little story i could share, give you guys a laugh.

[hifihaxor]

get pictures!

at central service center here, they have a set of 3 old 4kv/2.4 cast iron ge pots.. i think they were in a vault.. theyre really cool lookin... theyre in front of the building on display, we dont have any 4kv left here, but central is the oldest area we have.. lots of networked secondary and PILC.

[Koga]

We just took one down last Fri. night out of the ally. A 25 kva-4KV. The thing weighs 1,151 lbs. A new 100 KVA-20 KV weighs 1,150 .Im gonna use the tank as a wood stove after I clean it up.


Koga

[Squizzy]

Yep the good old transformers were built to last, back when they used to worry about quality of their equipment some of the old stuff is bomb-proof...

[mscheuerer]

I agree, I talked to a friend of mine in Cali last week during their heatwave and he told me how their newer units were physically blowing their lids apart on the poles but yet thee good ole cast iron jobs hung in their tough (with the exception of maybe a couple). Now im going to call him back and tell him how we're suffering here on the east coast. Lots of phasing and undervolt problems here recently. T&D says it's lines, line says it's CTO's (combustion turbine operators) CTO blames everything else...who do you believe?!

[altecworker]

i cant tell you how many times i have seen the voltage "brownout" today, probably 20 times at least. I have my thermostat set on 75, and I hope the ol bird holds on. The old GE is still in place, lol There is oil coming out from around the lid, but from what i understand, that is normal( i see it alot) The hospital therm read 117 today, in the sun, but the actual temp in the shade was 101. at this hour, 7:30, it is still 93

[altecworker]

question-

If a transformer's oil were replaced once every 20~ years, wouldnt the transformer last theoretically indefinetely?

Because one of the main reasons for failure is moisture intrusion into the oil, which reduced the dielectric capability, etc.

Or overloading, another failure point.

Heat kills the oil filled ones too, right?

[CenterPointEX]

Them old suckers gots lots of first rate copper in them... they are hearty I'll give em that... but that oil comming out around the lid tells me that lid will soon be launched...

[thrasher]

While testing and changing oil is often done on station power transformers and, at most companies, regulators also it's not justified for a standard pole-type transformer. If lightning, the local drunk or an overload doesn't get it a standard pole mount can last 50 years or more. I can take you to several hundred on my system alone. With that kind of life it is really hard to justify doing anything extra on a txf that only costs a few hundred dollars anyway, especially with the labor cost of testing or changing the txf. Now large padmounts or station class transformers do justify extra work. Here we test Power transformers every year and regulators every three years if the test comes back bad we pull maintenance.

[altecworker]

Launching the lid, that just means it's overfilled, and the pressure builds up?

Or, are we talking like explosive gas build-up here?

[BigClive]

Launching the lid, that just means it's overfilled, and the pressure builds up?

Or, are we talking like explosive gas build-up here?

I think we're talking breakdown of insulation value of old oil, leading to outgassing and pressure build up with lid popping results.

[CenterPointEX]

Well... when the xfmr oil gets over heated it produces Acetylene... then it when a spark or extremely high temps get to the Acetylene... It goes boom... The ensueing pressure in the xfmr lauhches the lid... I have closed in on this situation after a storm and seen the air filled with burning oil... raining down on my arse as I exited stage left...

[Hemingray Insulators]

I think they also taught us in Chem class that acetylene doesn't need a spark, that when it get to what they call critical density, that it can go off, can't remember if thats what they said or not.

[BigClive]

I think they also taught us in Chem class that acetylene doesn't need a spark, that when it get to what they call critical density, that it can go off, can't remember if thats what they said or not.

Yup. Axcetylene cyclinders have a special filling that absorbs the gas to keep it stable. Urban legend has it that an acetylene cylinder deliberately leaking gas out has been used to blow up vehicles.

Having worked in the industrial side of refrigeration I was exposed to many "demonstrations" of the explosive power of acetylene by pipe fitters who enyoyed doing the highly dangerous acetylene and oxygen in a big bag stunt. :)

[mscheuerer]

Yup. Axcetylene cyclinders have a special filling that absorbs the gas to keep it stable. Urban legend has it that an acetylene cylinder deliberately leaking gas out has been used to blow up vehicles.

Having worked in the industrial side of refrigeration I was exposed to many "demonstrations" of the explosive power of acetylene by pipe fitters who enyoyed doing the highly dangerous acetylene and oxygen in a big bag stunt. :)

BC YOU TOOK THE WORDS RIGHT OUT OF MY MOUTH!!! - Sounds like thee ole "Baggy Bombs" we used to make at work in the plant... Ahhh the supervisors loved us... One Hefty double sized trash bag filled with Acetylene from our trusty torch set, one drop light with the bulb "minorly" fractured and then the 100-200 feet of extension cord laid down the flight of steps awaiting for the potential Super to come strolling by....plugged it in and whammo!! Now those were the days before safety! We actually would put a diaper in their locker prior to doing this... :)

We won't get into how we used to launch the steel shot klinker balls out into the parking lot...that all had to stop after one unfortunatlely went through a windshield....

Hey what else do YOU do expect when working in a power plant???

[altecworker]

Presumably, it was refilled with new oil.

[Hemingray Insulators]

the new oil is the kind that can produce acetylene, I think it's mineral oil, correct me if I'm wrong.
the old pcb oil shouldn't do that, because it was usually what was called askarel (sp?) which was a non flamable coolant for liquid filled transformers. or supposededly it was, I don't know if that was really the case or not.

[altecworker]

well, let it boil to this!


Should I bother our great DukePoCo linemen about this thing, or should i let it be, and let er "blow"?

I am considering all of this on a history standpoint, the thing is old, built better than anything made today, and i see no problem with it, plus it's not a CSP so I dont have to stare at a red overload light.

[CenterPointEX]

You really don't want that oil all over your yard.... I will have pcbs in it...

[altecworker]

Well, that answers that, lol.


Reason I inquired about the oil, was, with the problems we've been having with the grid in Butner, I did not want to have a crew that could have been spending time doing something more important, come check a "oil leak" that was just some oil. Not enough to drip more than 2-3 oz onto the gravel under the pole. (8-10" round spot in gravel)

When the other unit failed, turns out the crew brought a 25kva 2.4kv unit with them on the truck, apparently assuming that unit would be the correct size, or were mis-informed. (my assumption)

I was told that they could not get a 50kva 2.4 unit within driving distance that night, but they had a "old" unit that was used and refilled with fresh oil, at the yard, so they installed it "temporarily" until they could get a new replacement. I told them, to just leave it, and not to bother bringing a new one. Due to the fact, I figured, "it's got fresh oil in it, which means it his full dielectric properties, which means it 'should' have lots of life left in it"

Granted, the presumed reason of failure of the original unit, was overload. That unit was 50kva, this unit is also 50kva, so it is subjected to the same loads as the previous unit.


Guys, I respect you for everything you are, stand for, and do.

I saw some ConEd trucks go out tonight, what the hell are they thinking with that "Tan, Blue and White" Paint Scheme, SHESH, it's ugly....


I used to be a big fan of Virgina Power's color scheme, the shade of gray, and the fire engine red was awesome.

Thanks for your time, Brian :D

[riverhog14]

Yeah a Ocala Electric has neon-green/yellow trucks. Pretty hard to miss. And speakin of neon colors, yall noticed the neon-colored seatbelts in use by FedEX? Sticks out when there wearing them even just passing by...