Construction of Transformer
Construction of Transformer
(OP)
Hi,
I'm curently involved in a cogeneration plant project. We have procured few auxiliary transformer. Our technical standards specify the followings:
"Oil-immersed transformers rated 1600 kVA and below shall be hermetically sealed. Transformers rated above 1600 kVA and up to 3150 kVA, may be either hermetically sealed or of the conservator type. However, hermetically sealed transformers above 3150 kVA shall be subject to Principal approval."
However, the supplier requested for deviation and propose to supply the non-hermetically sealed type transformer for 250 kVA. Is this common in industry?
Thanks
norzul
I'm curently involved in a cogeneration plant project. We have procured few auxiliary transformer. Our technical standards specify the followings:
"Oil-immersed transformers rated 1600 kVA and below shall be hermetically sealed. Transformers rated above 1600 kVA and up to 3150 kVA, may be either hermetically sealed or of the conservator type. However, hermetically sealed transformers above 3150 kVA shall be subject to Principal approval."
However, the supplier requested for deviation and propose to supply the non-hermetically sealed type transformer for 250 kVA. Is this common in industry?
Thanks
norzul






RE: Construction of Transformer
----------------------------------
Start each day with a smile. Get it over with.
RE: Construction of Transformer
Just wonder...for this small transformer why the supplier insist to supply the conservator type. From cost point of view I think it is more expansive. From maintenance point of view, looks like we may require more maintenance. It's like loose-loose situation not win-win...??
Fyi..the contract that we have is lump sum type i.e. we are not going to pay for the additional cost incurred by the supplier.
RE: Construction of Transformer
That logic doesn't entirely apply to your excitation transformer because loss of that one small transformer will shut down the generator just as effectively as loss of the GSU transformer, unless you are very lucky and have redundant excitation transformers. It would however be a relatively small task to remove and replace the excitation transformer if it failed, and relatively inexpensive to hold one as a spare for that eventuality.
So far as why so supplier wants to supply a conservator type, I can only guess that they have no experience of hermetic types, or are using a stock design rather than devloping a new one, or they have some stock of the conservator type already available.
----------------------------------
Start each day with a smile. Get it over with.
RE: Construction of Transformer
----------------------------------
Start each day with a smile. Get it over with.
RE: Construction of Transformer
RE: Construction of Transformer
I am not sure where you are located but in the USA I have not heard of 'hermetically sealed' transformers for normal distribution duty in the size you are specifying.
I would expect either a welded tank or gasketed bolted tank with a pressure relief valve, fill and drain valves, bolt on bushings, bayonet fuse etc; most of which would preclude 'hermetically sealed'.
I suggest you find a brand name you trust and go to their website or catalog and seek how their transformers are constructed, maybe check a couple of them out and write a spec about what you really need after seeing this.
RE: Construction of Transformer
Fyi, I'm currently involved in a cogeneration project, 120 MW (4 Gas Turbines + 4 Heat Recovery Steam Generators + 1 Steam Turbine). It is a lump sum turnkey kind of project. Now, the status is towards the end of detailed design/procurement phase. We'd issued POs for the GTs and ST. Our company's technical standards require hermetically sealed transformer for 1600 kVA and below.
The GT supplier complies with our stds. Unfortunately the ST supplier doesn't comply. The problem is, we just realized about this. Contractually we could still force them to comply....but...the schedule most likely will be affected & cause project delay...1st I try to convince myself that the conservator type is perfectly OK and perhaps more technically superior as compared to that of hermetically seal...before I go to my management for explanation...
Thanks
norzul
RE: Construction of Transformer
RE: Construction of Transformer
Read my previous post about standard specs for the size of transformer you anticipate. Hermetically sealled and Conservator both sound like oddballs for 1.6MVA.
RE: Construction of Transformer
RE: Construction of Transformer
The hermetically sealed type as mentioned earlier by ScottyUK claims to be "less maintenance" than conservator type. For the latter, one needs to replace the silica gel for the breather more often.
Electric,
Just wonder what is the normal distribution size of transformer used in USA if not as mentioned by norzul (1600kVA and below) ? FYI, hermetically sealed trx can be either adopted gas cushion (I presume same as nitrogen blanket) or thinner cooling fin system for 'breathing' purposes which are both acceptable in our MV distribution system.