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Consequence of Leak from main transformer tank to DETC Compartment

Consequence of Leak from main transformer tank to DETC Compartment

Consequence of Leak from main transformer tank to DETC Compartment

(OP)
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

RE: Consequence of Leak from main transformer tank to DETC Compartment

Depends on what type of tank design you have.  

RE: Consequence of Leak from main transformer tank to DETC Compartment

I'm confused.  The DETC and LTC are two different things in two different locations, aren't they?  

David Castor
www.cvoes.com

RE: Consequence of Leak from main transformer tank to DETC Compartment

(OP)
They are different, I made a typo.

RE: Consequence of Leak from main transformer tank to DETC Compartment

So your concern is leakage into the LTC compartment from the main tank?

I would discuss with the LTC manufacturer and transformer manufacturer.  But probably you can live for a little while like this.   

David Castor
www.cvoes.com

RE: Consequence of Leak from main transformer tank to DETC Compartment

I always assumed the LTC was separated from the main tank to protect the winding from the nasty stuff generated in the LTC that can make the LTC oil turn darker (carbon particles?).  I imagine it wouldn't be good for that nasty oil to soak into the paper insulation.

=====================================
(2B)+(2B)'  ?

RE: Consequence of Leak from main transformer tank to DETC Compartment

I would expect no issues with transformer oil leaking into the on-Load Tap Changer.
I would expect transformer failure in days or possibly hours if contaminated LTC oil leaks back into the transformer.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Consequence of Leak from main transformer tank to DETC Compartment

(OP)
I am sorry, I made the typo, it's DETC, not LTC compartment.

RE: Consequence of Leak from main transformer tank to DETC Compartment

For our transformers the DETC is in the main tank and LTC if present in a different compartment. You have DETC in different compartment?

=====================================
(2B)+(2B)'  ?

RE: Consequence of Leak from main transformer tank to DETC Compartment

(OP)
The leak has been lasted for many years.  And the DGA result shows normal.

RE: Consequence of Leak from main transformer tank to DETC Compartment

(OP)
Yes it is.  And it's with a liquid level gauge (always pointed to the max).

SInce DETC is in the main tank for some models, does this indicate it will be ok if liquid leaks from main tank to the DETC compartment?

RE: Consequence of Leak from main transformer tank to DETC Compartment

I've never seen a de-energized (off-load) tap changer in a separate compartment with a barrier.  Maybe you need to review the terminology and make sure you are describing the situation and components correctly.  Normally, separate compartments are for on-load tap changing mechanisms (LTC)



 

David Castor
www.cvoes.com

RE: Consequence of Leak from main transformer tank to DETC Compartment

(OP)
I attach the picture.

The compartment is called: Load Ratio Control Mechanism - Tap selector Compartment.

THe Liquid Lvl Gauge is for this compartment.

RE: Consequence of Leak from main transformer tank to DETC Compartment

The key word is load. The taps change under load, so there is arcing occurring in the oil. LTCs are usually free breathing, so moisture level is much higher. You do not want this dirty wet oil in your main tank.

RE: Consequence of Leak from main transformer tank to DETC Compartment

(OP)
Steven, it's a DETC transformer

RE: Consequence of Leak from main transformer tank to DETC Compartment

Perhaps your transformer also has a de-energized tap changer on the primary winding. The compartment that you identified as "load ratio control - Tap selector" is also known as an on-load tap changer.

RE: Consequence of Leak from main transformer tank to DETC Compartment

It's a rather important distinction to understand. The consequence of not knowing could be fatal.

RE: Consequence of Leak from main transformer tank to DETC Compartment

(OP)
Thank you Steven,

Yes you're right, the "On Load Tap Changer" is on the X side.  It's my mis-understanding to identify it as the DETC.

So we may put in this way?

- The compartment of OLTC is much less sealed.  There is no much acr generated in that compartment (not much comtamination), since it has never been operated.  But if it starts to be operated, serious contamination will occur, and it can do the real damage to the transformer.

RE: Consequence of Leak from main transformer tank to DETC Compartment

Never? Sounds like a long time for a transformer that does not appear to be very new. Voltage regulating controls are and have always been locked off? I'd be hesitant to trust the expense of a transformer to hearsay. Test the oil to confirm.
In my experience, the locked off LTCs collect just as much if not more moisture than those running in automatic.

RE: Consequence of Leak from main transformer tank to DETC Compartment

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

RE: Consequence of Leak from main transformer tank to DETC Compartment

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

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

RE: Consequence of Leak from main transformer tank to DETC Compartment

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.
  

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

RE: Consequence of Leak from main transformer tank to DETC Compartment

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.

RE: Consequence of Leak from main transformer tank to DETC Compartment

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

RE: Consequence of Leak from main transformer tank to DETC Compartment

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.
  

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

RE: Consequence of Leak from main transformer tank to DETC Compartment

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.
 

=====================================
(2B)+(2B)'  ?

RE: Consequence of Leak from main transformer tank to DETC Compartment

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

=====================================
(2B)+(2B)'  ?

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