Consequence of Leak from main transformer tank to DETC Compartment

[Beengineer]

One of our transformer has the leaks from main tank to the DETC compartment, likely the Barrier board between LTC & main tank failed due to faulty gasket.

What's the consequence if we leave it un-fixed soon?

Thanks

 

[Beengineer]

This is a 1956 transformer. I thought OLTC was for much newer transformers.

 

[ScottyUK]

Oh no, OLTCs have been around for a very long time.


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If we learn from our mistakes I'm getting a great education!

 

[ScottyUK]

I was curious: The Reinhausen company developed the diverter-type on-load tapchanger in 1926. Their products are still among the very best available, some might argue they are the best.


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If we learn from our mistakes I'm getting a great education!

 

[prc]

Scotty, there was OLTC for more than 100 years.In 1910, ASEA came out with an OLTC called HM which was popular for many years.During the same period,American and English companies also had models of OLTC. It is true that MR was the first to develop high speed resistor type tapchangers.But almost all transformer companies had their own tap changer models.But the business setbacks in 1960's to 70's compelled transformer companies to stop manufacture of OLTCs and stick to their 'core competencies'.Last to do that was Elin in late90's.Today there are only two models or manufacturers with worldwide coverage -ABB &MR.Of course there are many manufacturers of OLTC in the emerging economies with various models.

Coming to Beengineers query -Dont worry nothing is going to happen.You have said that DGA of main tank oil is OK. It means either the device is DETC,but more probably the leakage is from the tap-selector tank of OLTC and not from the diverter switch tank( where arcing occurs).In 50's and 60's it was a practice of some customers to demand tap selector part also in a separate tank.You can verify this by having a look at the rating and connection diagram plate and also service manual ,if available.

Even if the minor leak is from arcing chamber,normally it will not cause much problem for short periods except for the nuisance of obscuring trf DGA analysis and need for filtering main tank oil after rectifying the leak.

 

[Beengineer]

prc, You're right. I was wondering why it's called Tap Selector Compartment, not "OLTC" compartment.

 

[ScottyUK]

If this is a conservator type transformer - a reasonable guess if it is big enough to have an OLTC - then a practical solution in the short / medium term would be to maintain the main tank conservator oil level slightly higher than that for the diverter tank, so any differential head will force leakage from the clean oil into the dirty.

You may have to periodically draw some oil off from the diverter sample point to maintain the pressure differential if the leak is signficant or you are going to run for a prolonged period before maintenance takes place.


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If we learn from our mistakes I'm getting a great education!

 

[electricpete]

Good comment - I was thinking to add a similar comment about relative pressures as well.

Some other related things to consider:
1 – dp drives the leak rate so there may be potential to overflow the LTC compartment.
2 – Diffusion can allow contaminants to travel opposite the direction of slow bulk fluid flow, so don’t get a false sense of security from the dp. It is very common to see the oiler reservoir feeding rotating machine bearings turn grey from bearing oil contaminants (like wear of brass slinger rings), even though the oiler reservoir is at a higher level than the bearing.


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(2B)+(2B)' ?

 

[electricpete]

Item 1 was already addressed by Scotty - sorry for repeating.

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(2B)+(2B)' ?