Cutting over 167kva (or larger) XFMR'S

[hotwiretamer]

Just curious if on 167kva or larger xfmr's (with 4 bushings), are you still lifting the lid and moving the straps, or building jumpers on the outside off of the bushings. I've done it both ways, but some of the leads are mighty stiff to move around inside the larger xfmr's

[kooman]

we allways jump them on the outside.

[Pootnaigle]

Ummmmmmmmm US too, Didnt ever wanna take a chance of dropping a nut or sumpin in that oil, and sometimes them lids iz contrary to get back on.

[bren guzzi]

After they've been running the oil gets heavily contaminated with P C B,s. We don't EVER take the tops off... Enviromental hazard. POLYCHLORINATED BIPHENY. !!!!!!!! Google it ( gives ya cancer)

[BigClive]

I've heard of PCB filled transformers and oil filled transformers, but not leaching of PCBs into oil. From the winding insulation?

[bren guzzi]

I've heard of PCB filled transformers and oil filled transformers, but not leaching of PCBs into oil. From the winding insulation?

I know a lot of big substations have trouble with pcbs in the oil. I often had to bring oil samples to the lab for testing when refurbishing for the GRID. But they also "I believe hav (or had trouble with pole mounted)..... Maybe it was mineral oil and its changed Now. Not sure. But was a prob with transformers when "I was a lad". But things may have changed. Just putting it out there. I don't have anything to do with transformer oil. We never open them. More research req me thinks. :)

[Pootnaigle]

Ummmmmmm I bleve all new transformers are filled with mineral oil or sumpin similar and most of em are labeled NON PCB .Cowpastures however may well still contain PCBs.Aint no opening innem for changing or draining the oil kause they are sealed up airtight... Never heard of leaching but I dont reckon I am the ultimate authority on that.

[lewy]

Not an issue with us if the customer requires more than 150 kva they have to go to a pad mount.

[hotwiretamer]

Not an issue with us if the customer requires more than 150 kva they have to go to a pad mount.

Normally that is the case for us too, however recently we had to change out a pole and existing xfmr bank. The existing was cut-over inside, and that is what brought up the question.

[Pootnaigle]

Ummmmmmm well It just dont make much sense to me to open a pot n get oil all over yer hands, n take a chance on droppin a nut er a wrench er sumpin down into the core when ya aint gotta. N if ya have 4 secondary bushings ya just aint gotta. Course it mite be easier than hanging a padmount onna pole.

[reppy007]

Ummmmmmm I bleve all new transformers are filled with mineral oil or sumpin similar and most of em are labeled NON PCB .Cowpastures however may well still contain PCBs.Aint no opening innem for changing or draining the oil kause they are sealed up airtight... Never heard of leaching but I dont reckon I am the ultimate authority on that.

Had a guy that was the head, on a capacitor crew back in the mid 80s.He was sent to different locations to remove capacitors that most likely had pcb's.Everyone thought he did a average job,no superman,just a reg friendly guy.Well every was wrong,although he did remove some with the non-pcb name-plates ,he would also ride around visiting friends and such.Well this one time the utility gets a call stating that a pole is on fire,some of you know where this is leading.Yes ,the pole that was reported on fire turned out to be a cap bank,and worse that cap bank had pcb,s,and to make things worse he filled out paper-work stating that it was up-dated.Saying he removed the bad capacitors.Just his bad luck,they blew up ,oil all over a customers backyard,his fence,even his swimming pool.Guess i didnt have to tell you this,but in case you are wondering,he was fired pretty fast.

[jozmo]

After they've been running the oil gets heavily contaminated with P C B,s. We don't EVER take the tops off... Enviromental hazard. POLYCHLORINATED BIPHENY. !!!!!!!! Google it ( gives ya cancer)The pcbs are in the oil when it was put in the transformer

[topgroove]

The pcbs are in the oil when it was put in the transformer

PCB's can also develope inside even mineral based transformer oil. Its an electro chemical reaction that can produce PCB.

If you read the sticker on the can it carefully states Non-PCB at time of manufacturer.

Once the transformer is put in service all bets are off.

[Pootnaigle]

Ummmmm well I reckon a feller just dont never get done lurnin. Thanks for sharing that kause I sho nuff dint know it.

[hotwiretamer]

Ummmmmmm well It just dont make much sense to me to open a pot n get oil all over yer hands, n take a chance on droppin a nut er a wrench er sumpin down into the core when ya aint gotta. N if ya have 4 secondary bushings ya just aint gotta. Course it mite be easier than hanging a padmount onna pole.

I totally agree. Here's another question:
We actually transfered the old bank that was cut-over inside. (Due to our warehouse only having two 167's at the right voltage.) Sure enough now we have one that is leaking! After a xfmr sits on a pole for 40 yrs. and you start messing with the leads and bushings, they tend to leak!
Now, we will be changing out that pot. Do you cut it over inside to match the others, or just build your leads outside the new pot to get your windings in parallel???

[Pootnaigle]

Ummmmm wait til yer storeroom haz 3 new uns. Put the old uns in them fancy PCB barrells n get shed of em ferever.

[topgroove]

Ummmmm wait til yer storeroom haz 3 new uns. Put the old uns in them fancy PCB barrells n get shed of em ferever.

I agree... I hate those mix and match banks. You really have to take a good look at the nameplate on the transformer too... You'ld be suprised how many times the impediance dosen't match, which causes the power factor to become a problem.

[hotwiretamer]

I agree... I hate those mix and match banks. You really have to take a good look at the nameplate on the transformer too... You'ld be suprised how many times the impediance dosen't match, which causes the power factor to become a problem.

Agreed. Hopefully one of the two we have will be close enough! Not a lot of common sense at our warehouse! God forbid we have three of the same voltage, let alone the same impedence!!:eek:

[barehander]

PCB's can also develope inside even mineral based transformer oil. Its an electro chemical reaction that can produce PCB.

If you read the sticker on the can it carefully states Non-PCB at time of manufacturer.

Once the transformer is put in service all bets are off.

That has to be the biggest bunch of BS I've ever heard.............prove it!

[Lineman North Florida]

Most of the stickers that I see on new transformers say Less than 1 PPM meaning that it has less than 1 part per million. We have had some old transformers that were definately PCB contaminated, I talked with a guy who is a long time rep from one of the company's that we buy our transformers from and he told me anything manufactured from about 1990 on would be PCB free, our transformer shop doesn't even come out to test for PCB's unless we get a pot without that sticker on it, so if transformers make PCB's we have probably left a lot of it.:D

[topgroove]

That has to be the biggest bunch of BS I've ever heard.............prove it!

Your absoulutly right Bro.... In your case,, Don't worry about a thing. Its perfectly safe. Put the stuff on your salad, or a lube for your private moments for all I care.

[barehander]

http://www.powerlineman.com/lforum/images/misc/quote_icon.png Originally Posted by topgroove http://www.powerlineman.com/lforum/images/buttons/viewpost-right.png (http://www.powerlineman.com/lforum/showthread.php?p=117350#post117350)
PCB's can also develope inside even mineral based transformer oil. Its an electro chemical reaction that can produce PCB.

If you read the sticker on the can it carefully states Non-PCB at time of manufacturer.

Once the transformer is put in service all bets are off.

http://www.powerlineman.com/lforum/images/misc/quote_icon.png Originally Posted by barehander http://www.powerlineman.com/lforum/images/buttons/viewpost-right.png (http://www.powerlineman.com/lforum/showthread.php?p=117362#post117362)
That has to be the biggest bunch of BS I've ever heard.............prove it!


Your absoulutly right Bro.... In your case,, Don't worry about a thing. Its perfectly safe. Put the stuff on your salad, or a lube for your private moments for all I care.


I could respond to this in so many ways..........but your response is so predictable when you are caught in a lie. You reply with some condescending response attacking the person. When you state fiction as fact, you need to be called on it. If you can't back it up, then say so. A lot of people on this site read this stuff, and they deserve the truth. You stated the above, and a lot of people here didn't even question it and I'm stunned. They even patted you on the back for informing them on this miracle in Chemistry. I guess the Periodic Table of Elements works differently where you live. Tell us all on Powerlineman.com how mineral oil can be transformed into PCB by waving that "Magic Electromagnetic Wand".......

[wantafastz28]

A lot of people on this site read this stuff, and they deserve the truth. You stated the above, and a lot of people here didn't even question it and I'm stunned. They even patted you on the back for informing them on this miracle in Chemistry. I guess the Periodic Table of Elements works differently where you live.[/FONT][/COLOR][/SIZE] Tell us all on Powerlineman.com how mineral oil can be transformed into PCB by waving that "Magic Electromagnetic Wand".......

What this guy said... when he posted that, i spent like 20-30 minutes looking it up cause I've never heard of that before.

[jozmo]

What this guy said... when he posted that, i spent like 20-30 minutes looking it up cause I've never heard of that before.

Me either .

[topgroove]

http://www.powerlineman.com/lforum/images/misc/quote_icon.png Originally Posted by topgroove http://www.powerlineman.com/lforum/images/buttons/viewpost-right.png (http://www.powerlineman.com/lforum/showthread.php?p=117350#post117350)
http://www.powerlineman.com/lforum/images/misc/quote_icon.png Originally Posted by barehander http://www.powerlineman.com/lforum/images/buttons/viewpost-right.png (http://www.powerlineman.com/lforum/showthread.php?p=117362#post117362)
That has to be the biggest bunch of BS I've ever heard.............prove it!




I could respond to this in so many ways..........but your response is so predictable when you are caught in a lie. You reply with some condescending response attacking the person. When you state fiction as fact, you need to be called on it. If you can't back it up, then say so. A lot of people on this site read this stuff, and they deserve the truth. You stated the above, and a lot of people here didn't even question it and I'm stunned. They even patted you on the back for informing them on this miracle in Chemistry. I guess the Periodic Table of Elements works differently where you live. Tell us all on Powerlineman.com how mineral oil can be transformed into PCB by waving that "Magic Electromagnetic Wand".......

Transformer oils are subject to electrical and mechanical stresses while a transformer is in operation. In addition there is contamination caused by chemical interactions with windings and other solid insulation, catalyzed by high operating temperature. As a result the original chemical properties of transformer oil changes gradually, rendering it ineffective for its intended purpose after many years.

We have to test any transformer we change out that is leaking, even the slightest leak.
At Grid we use the CLOR-N-OIL 50 PCB disposable test kit made by Dexsil Corporation.
The kit will show positive if PCB contamination is greater than 50 PPM.

I've never counted Positive tests over the years but I'm sure I've had over ten positives on tubs that had a non-PCB sticker on them.
If your test sample appears purple it contains less than 50 PPM PCB, if it shows yellow or clear it MAY contain more than 50 PPM and the tub is sent to our lab for further testing for a PCB specific method.

Now, I don't know if the test was simply a false positive or not. All I know is that I'm old enough to remember when Asbestos was perfectly safe, seat belts were optional and lead based paint was used on baby cribs.

If you want to stick your hands in used transformer oil, Hey..... Have at it Barehander

Take a bath and soak in the stuff for all I care.


For the younger guys a little caution can go along way... Its kinda strange I've been to so many wakes for retired lineman over the years who died of cancer.

[jozmo]

Transformer oils are subject to electrical and mechanical stresses while a transformer is in operation. In addition there is contamination caused by chemical interactions with windings and other solid insulation, catalyzed by high operating temperature. As a result the original chemical properties of transformer oil changes gradually, rendering it ineffective for its intended purpose after many years.

We have to test any transformer we change out that is leaking, even the slightest leak.
At Grid we use the CLOR-N-OIL 50 PCB disposable test kit made by Dexsil Corporation.
The kit will show positive if PCB contamination is greater than 50 PPM.

I've never counted Positive tests over the years but I'm sure I've had over ten positives on tubs that had a non-PCB sticker on them.
If your test sample appears purple it contains less than 50 PPM PCB, if it shows yellow or clear it MAY contain more than 50 PPM and the tub is sent to our lab for further testing for a PCB specific method.

Now, I don't know if the test was simply a false positive or not. All I know is that I'm old enough to remember when Asbestos was perfectly safe, seat belts were optional and lead based paint was used on baby cribs.

If you want to stick your hands in used transformer oil, Hey..... Have at it Barehander

Take a bath and soak in the stuff for all I care.


For the younger guys a little caution can go along way... Its kinda strange I've been to so many wakes for retired lineman over the years who died of cancer.More likely than not most false positives caused by sweat or out of date kit.

[topgroove]

More likely than not most false positives caused by sweat or out of date kit. that may be true but I've always felt its better to err on the side of caution.

Take it for what its worth, Its your life. Who knows what contamination is in the oil.... PCB or not.

[barehander]

Transformer oils are subject to electrical and mechanical stresses while a transformer is in operation. In addition there is contamination caused by chemical interactions with windings and other solid insulation, catalyzed by high operating temperature. As a result the original chemical properties of transformer oil changes gradually, rendering it ineffective for its intended purpose after many years.

We have to test any transformer we change out that is leaking, even the slightest leak.
At Grid we use the CLOR-N-OIL 50 PCB disposable test kit made by Dexsil Corporation.
The kit will show positive if PCB contamination is greater than 50 PPM.

I've never counted Positive tests over the years but I'm sure I've had over ten positives on tubs that had a non-PCB sticker on them.
If your test sample appears purple it contains less than 50 PPM PCB, if it shows yellow or clear it MAY contain more than 50 PPM and the tub is sent to our lab for further testing for a PCB specific method.

Now, I don't know if the test was simply a false positive or not. All I know is that I'm old enough to remember when Asbestos was perfectly safe, seat belts were optional and lead based paint was used on baby cribs.

If you want to stick your hands in used transformer oil, Hey..... Have at it Barehander

Take a bath and soak in the stuff for all I care.


For the younger guys a little caution can go along way... Its kinda strange I've been to so many wakes for retired lineman over the years who died of cancer.

I live in the most environmentaly sensitive part of this country and nothing you have posted tells me that some magical thing happened with mineral oil. All it says is that the oil breaks down and it's insulating qualities deteriate. We send all our oil to a test facility. Never has a non-pcb tx ever came back as positive. 50ppm is high from a mineral based tx that says Non-PCB, and doesn't make sense at all. Flourinated Hydrocarbons do not magically turn into Polyclorinatedbiphenyls.
And by the way, I have had my hands in many transformers before PCB's were banned and nothing has fallen off.
Unfortunatley, cancer also happens to people who have never had their hands in PCB oil.

[topgroove]

Good for you bro... like I said enjoy:)

[barehander]

Good for you bro... like I said enjoy:)

Come on now, answer the question, don't dodge me.

[topgroove]

Come on now, answer the question, don't dodge me.

I will never dodge a question. I am not a chemist and have no idea how contaminants are produced within a transformer.

All I am doing is sharing my expierence and contributing in this thread. Some of the leaking transformers I have tested have shown positive with the field test. Like I said, maybe its a false positive.
Just like industrial oils, transformer oils, I have been told are oxidized under the influence of excessive temperature and oxygen, particularly in the presence of small metal particles which act as catalysts, resulting in an increase in Acid Number, due to the formation of carboxylic acids. Further reaction can result in sludge and varnish deposits.

Ever look inside a used transformer? If its pure mineral oil whats that weird color and smell? I'm not sure but last time I checked carboxylic acid was the nasty stuff in poison mushrooms.

But your probebly right barehander.... I'm sure the stuff is as safe as baby oil.

Hey I have an Idea Barehander, Tommorrow at work, why don't you get real close to the vent valve on a tub. Get your nose right next to it and light a lighter in front of the vent and give it a pull. Its only mineral oil.... It can't hurt you.

[bren guzzi]

You. Guys crack me up.! It was me that mentioned pcbs in the first place in relation to this thread. An you guys start useing it as a weapon to beat each other up. Ha ha. Grow up guys and do your own reserch. BE LUCKY. X

[rcdallas]

<....delete....>

[topgroove]

For the younger guys out there.... If you can avoid sticking your hands in used transformer oil do it. If you must, make sure you clean your hands really well after. try not to eat or drink and god forbid smoke, till you hands are clean. Who the hell knows what weird $hit is in there! if not for yourself your future family.

I'm old enough to remember when lots of stuff was perfectly safe. When I was a eighteen year old kid in the navy the asbestos used to fall from the pipes and overhead like snow above my bunk.

[barehander]

I will never dodge a question. I am not a chemist and have no idea how contaminants are produced within a transformer.

All I am doing is sharing my expierence and contributing in this thread. Some of the leaking transformers I have tested have shown positive with the field test. Like I said, maybe its a false positive.
Just like industrial oils, transformer oils, I have been told are oxidized under the influence of excessive temperature and oxygen, particularly in the presence of small metal particles which act as catalysts, resulting in an increase in Acid Number, due to the formation of carboxylic acids. Further reaction can result in sludge and varnish deposits.

Ever look inside a used transformer? If its pure mineral oil whats that weird color and smell? I'm not sure but last time I checked carboxylic acid was the nasty stuff in poison mushrooms.

But your probebly right barehander.... I'm sure the stuff is as safe as baby oil.

Hey I have an Idea Barehander, Tommorrow at work, why don't you get real close to the vent valve on a tub. Get your nose right next to it and light a lighter in front of the vent and give it a pull. Its only mineral oil.... It can't hurt you.



For the original question, no need to take the lid off, it can be wired externally.

I don't disagree with you that mineral oil can become contaminated, but not with PCB. We do not test blue stickered txs that say non-pcb, the State agrees with that, and they are very strick on the reporting process. Sulfer & moisture affects your little test kit, and I would guess you're getting false positives.
Some of us old guys started before PCB was banned, so yes, I have had my hands in oil that probably contained PCB. Tell me where in any of my posts that I said it was safe. You just decided to take a poke at me, but that's ok. PCB is serious business where I live and is handled apropriately. My State is so bad that when a pole is pulled out of the ground, it is now Hazardous Waste. If you cut it up to haul it in, you have to pick up all the sawdust because it is Hazardous Waste and all of it it placed in a special bin. No more giving poles or crossarms away to the farmers and ranchers because you can be criminally charged with dispersing hazardous waste.
So feel free to keep saying that I said how safe it was, just make sure it's an actual quote made by me.

[lewy]

We had a program of testing all of our transformers & removing any that had P.C.Bs, if my memory is correct the big danger was if the oil was on fire.

[BigClive]

For the younger guys out there.... If you can avoid sticking your hands in used transformer oil do it. If you must, make sure you clean your hands really well after. try not to eat or drink and god forbid smoke, till you hands are clean. Who the hell knows what weird $hit is in there! if not for yourself your future family.

I'm old enough to remember when lots of stuff was perfectly safe. When I was a eighteen year old kid in the navy the asbestos used to fall from the pipes and overhead like snow above my bunk.

Also avoid scratching your balls if you get oil on your hands. Some can be quite a fiery experience down there! :eek:

With regards to asbestos when it was not known to be so hazardous... I worked alongside some old electricians who had spent their youth in the shipyards and used to have snowball fights with handfulls of asbestos fluff.

For those who don't know what the legendary blue asbestos looks like, it's a blue fluff like the lint you find in your jeans pockets, belly button, tumble dryer lint filter or vacuum cleaner. It used to be used loose to fill between walls for fireproofing, particularly in old cinemas between the projection room and auditorium. If you ever break through a wall and find blue fluff inside then don't breath the dust in.

[rob8210]

Field tests for PCB's are just that field tests. They are not extremely accurate and they are very sensitive to moisture. They are only meant to warn you to be extra cautious, just in case. I worked at one utility that if the field test was positive, then a sample went directly to a lab, immediately. We waited for the lab results before we carried on. As for changing transformers for power bank connections where I am currently contracted they use cans with 4 secondary bushings and all connections are done external. No need to lift lids any more. I have heard that PCB's were banned anywhere from 1977 to 1982.

[hotwiretamer]

The old 167's are labelled 2.6, and the new 167 we have to replace the leaker is 2.6. I'm thinking that's too much difference, but the GF doesn't think that it will be a prob. What's your opinions?:confused:

[topgroove]

Little confused hotwire... is that a mistype? Both tubs are 2.6 Impedence?

[hotwiretamer]

Little confused hotwire... is that a mistype? Both tubs are 2.6 Impedence?

Ooops.... The existing bank has 2.6. The new pot is 1.6.

[kooman]

i could be wrong but i thought the only time you need to worry about imp. matching was on a delta delta bank?

[rob8210]

I have always been told that the impedance must be within 10%. In this case no lower than 2.3 and no higher than 2.9

[topgroove]

I have always been told that the impedance must be within 10%. In this case no lower than 2.3 and no higher than 2.9

Yep... 10% is what we shoot for here too!

Believe it or not impedence is kinda important if you want balanced voltage on the customers three phase service. Matching KVA is important too. I hate those mix and match banks I see in the air sometimes.

Here's a program that calculates the secondary voltage for you... Not sure how much the software costs?
http://www.dstar.org/research/project-desc/GSVIC/